1. Didn't the Rebel Alliance win? What went wrong with that?

The Rebellion did indeed topple the Empire after Return of the Jedi and founded a Republic. But that Republic appears to have been a breeding ground for what became the First Order, according to this thought of Leia's:

Those who had led the rebellion had under-estimated the deeply buried desire of far too large a proportion of the population who simply preferred to be told what to do. Much easier it was to follow orders than to think for oneself. So everyone had argued and debated and discussed. Until it was too late.

2. What is the First Order's philosophy?

In the movie, General Hux does a lot of shouting about the glory of the First Order and the end of the Republic, but that doesn't tell you what the Order is trying to achieve. In the book, Kylo Ren sums it up far better while showing an underling the beam of solar energy from Starkiller base:

A gloved hand rose to take in the sweep of light and energy arrayed before them.

“Look at it, Lieutenant. So much beauty among so much turmoil. In a way, we are but an infinitely smaller reflection of the same conflict. It is the task of the First Order to remove the disorder from our own existence, so that civilization may be returned to the stability that promotes progress. A stability that existed under the Empire, was reduced to anarchy by the Rebellion, was inherited in turn by the so-called Republic, and will be restored by us. Future historians will look upon this as the time when a strong hand brought the rule of law back to civilization.”

[Lieutenant] Mitaka forbore mentioning that the Republics had developed their own codes of law. To do so would have been … indelicate, and he doubted that Ren was in the mood for a political discussion of any kind.

3. Why was Han Solo transporting those troublesome Rathtars?

We get a very brief explanation in the movie for why everyone's favorite smuggler is shlepping monsters with nasty suckers, but here it is in full:

“I got three going to King Prana. Kings not only like to collect, they like to boast about their collections. Seems Prana’s in competition with the regent of the Mol’leaj system. The regent doesn’t have a rathtar in his private zoo. Neither does anybody else.”

“There’s a reason for that,” Finn muttered.

4. Was Leia in touch with the Republic?

In the movie, you're never quite sure of the relationship between General Leia Organa's Resistance and the Republic for which it fights. In the book, Leia reveals that it's pretty contentious, because the Senate has gone off the deep end. Indeed, she fears her life will be at risk if she goes to plead the case for more force.

Here she is, talking to her personal envoy to the Republic, Korr Sella:

“You need to go to the Senate right away. Tell them I insist that they take action against the First Order. The longer they bicker and delay, the stronger the Order becomes.” She leaned toward the other woman. “If they fail to take action soon, the Order will have grown so strong the Senate will be unable to do anything. It won’t matter what they think.”

Sella indicated her understanding. “With all respect: Do you think the senators will listen?”

“I don’t know.” Leia bit down on her lower lip. “So much time has passed. There was a time when they were at least willing to listen. And of course, the Senate’s makeup has changed. Some of those who were always willing to pay attention to me have retired. Some of those who have replaced them have their own agendas.” She smiled ruefully. “Not all senators think I’m crazy. Or maybe they do. I don’t care what they think about me as long as they take action."

5. Was Starkiller base a weapon that was turned into a planet, or a planet that turned into a weapon?

The movie barely gives you any time to look at the base's exterior, let alone answer that chicken-and-egg question. The book has no such problems:

Spectacular and isolated, with a mean surface temperature varying from merely cold to permanently arctic, the planet had been altered: its mountains tunneled into, its glaciers hacked, and its valleys modified until it no longer resembled its original naturally eroded form. Those who had remade it had renamed it.

6. Why exactly did the First Order fire on those planets?

Since the Starkiller attack comes out of the blue, pretty much, you may have been confused about what General Hux was trying to do and why the planets that were destroyed ("the Hosnian system") mattered. The book makes clear that the Senate was meeting there. Here's Hux outlining his strategy, such as it is:

The redheaded officer spoke up immediately. “I do have a proposition. The weapon. We have it. It is ready. I believe the time has come to use it.”

“Against?”

“The Republic. Or what its fractious proponents choose to call the Republic. Their center of government, its entire system. In the chaos that will follow, the Resistance will have no choice but to investigate an attack of such devastating scale. They will throw all their resources into trying to discover its source. So they have no choice but to investigate fully, and in so doing…”

“Reveal themselves.”

Snoke was clearly pleased.

“And if they don’t… we’ve destroyed them.”

“Yes,” Snoke said in satisfaction. “Extreme. Audacious. I agree that the time for such measures has come. Go. Oversee the necessary preparations.”

7. How far back does Supreme Leader Snoke go?

Okay, so the big bad guy displayed in that giant hologram is some sort of powerful dark side figure. Only the book will suggest that he's been around for a long time — at least 50 years, back before the Empire was founded. In other words, he hails from the prequel era — and he has a whole lot of ideas about why things didn't go well for the dark side during the original trilogy.

“Kylo Ren, I watched the Galactic Empire rise, and then fall. The gullible prattle on about the triumph of truth and justice, of individualism and free will. As if such things were solid and real instead of simple subjective judgments. The historians have it all wrong. It was neither poor strategy nor arrogance that brought down the Empire. You know too well what did.”

Ren nodded once. “Sentiment.”

“Yes. Such a simple thing. Such a foolish error of judgment. A momentary lapse in an otherwise exemplary life. Had Lord Vader not succumbed to emotion at the crucial moment — had the father killed the son — the Empire would have prevailed. And there would be no threat of Skywalker’s return today.”

8. How did Poe Dameron get back from his crashed TIE fighter?

Simple — he gets picked up by a passing speeder and has a not-so-exciting adventure. It begins this way:

A dark spot appeared between the dunes, expanding rapidly as it came toward him. Flat in front and bulging at the stern, the speeder was an unlovely construct, but to Poe at that moment it had lines as sweet as those of the fastest fighter in the Resistance fleet. Standing in the middle of the salt flat, he began jumping up and down and waving his arms.

9. Did whoever left Rey on Jakku mean to come back for her?

Apparently, yes. Rey hears a mysterious voice, a recognizable but mysterious one, at the end of her lightsaber vision:

Once more she climbed to her feet, her chilled breath preceding her. From in front of her, not far away, came the sounds of battle: the cries of the wounded and the clashing of weapons. Then behind her, another voice. That voice.

“Stay here. I’ll come back for you.”

She whirled, glazed eyes desperately scanning the dark gaps between the slender trees, trying to penetrate the darkness. “Where are you?” She started running toward the voice.

“I’ll come back, sweetheart. I promise.”

10. How strong is Leia with the Force?

As strong as Obi-Wan Kenobi, it would seem. In the book, she feels the destruction of the Hosnian system in the same way Kenobi felt the destruction of Alderaan:

Leaning against a console for support, she steadied herself. “A great disturbance — in the Force. Deaths and passings. Too much death, too many passings.”

11. Did Maz Kanata change her mind about Finn?

Yup. After the whole bit where the diminutive bar owner adjusts her goggles to see "a man who wants to run" in Finn's eyes, after the battle that ensues, Maz Kanata takes one more look at the former Stormtrooper and says:

“Oh wow… I see something else now.”

“See what?” Finn asked.

“I see the eyes of a warrior.”

12. Were Han and Leia actually married?

This isn't made clear in the film — just that they had a son together. The existence of nutpials (and no divorce!) is confirmed in the book, however, which tells us on their first meeting that "husband and wife stood regarding each other for the first time in years."

13. Is Rey related to Han and Leia?

It looks increasingly unlikely, given that Han and Leia casually refer to Rey as "the girl." Here's what Finn says to Leia when he asks to meet her:

"I’m here to talk about a friend of mine who was taken prisoner during the clash on Takodana.”

She nodded understandingly. “Han told me about the girl. I’m sorry.”

14. When did Snoke start to turn Kylo Ren to the dark side?

Here's an interesting bit worth quoting at length. In the movie, Leia tells Han she's sure Snoke has turned their basically good child to the dark side. In the book, she reveals this has been going on for 30 years:

“He knew our child would be strong with the Force. That he was born with equal potential for good or evil.”

“You knew this from the beginning? Why didn’t you tell me?”

She sighed. “Many reasons. I was hoping that I was wrong, that it wasn’t true. I hoped I could sway him, turn him away from the dark side, without having to involve you.”
A small smile appeared. “You had— you have— wonderful qualities, Han, but patience and understanding were never among them. I was afraid that your reactions would only drive him farther to the dark side. I thought I could shield him from Snoke’s influence and you from what was happening.”

Her voice dropped. “It’s clear now that I was wrong. Whether your involvement would have made a difference, we’ll never know.”

He had trouble believing what he was hearing. “So Snoke was watching our son.”

“Always,” she told him. “From the shadows, in the beginning, even before I realized what was happening, he was manipulating everything, pulling our son toward the dark side. But nothing’s impossible, Han. Not even now, at this late time. I have this feeling that if anyone can save him— it’s you.”

15. Why did Starkiller base have an 'oscillator'?

The weakness in the giant Death Star — sorry, I mean Starkiller base — was its oscillator. But why would a planet need to oscillate? Here's the explanation from Admiral Statura, the Resistance leader played by Ken Leung (the guy from Lost).

Statura, we're told, is "the most senior officer in the room with an actual scientific background" — whatever that means in the basically science-free Star Wars universe:

Statura was deep in thought. “A planetary magnetic field, even a strong one, would not be enough to contain the amount of energy that we have seen deployed. Also as you say, Finn, there is more involved. I am thinking some kind of oscillating field. If it oscillates rapidly enough, much less energy would be required to sustain it than if it was maintained at a steady state.”

16. Was there something more Han wanted to say to Leia?

Yes. Time to grab another Kleenex, because there's extended dialogue when the couple say goodbye:

He put his hands on her shoulders, and thirty years fell away in an instant.

“Leia, there’s something I’ve been wanting to say to you for a long time.”

Fighting to hold back tears, she put a finger to his lips. “Tell me when you get back.”

17. Why did Captain Phasma give up so easily?

Gwendoline Christie's character was kind of a pushover in the movie, lowering the shields and making Starkiller base defenseless just because Han and Finn were pointing blasters at her. In the book, Chewbacca applies more pressure — literally.

She managed a slight shake of her head. “Even a Wookiee can’t crush First Order armor.” In response, Chewbacca tightened his grip further. Her mask emitted a slight but perceptible wheeze.

“Well,” Han said nonchalantly, “there’s one way to find out.”

18. Did Rey's scavenging past come in useful?

It did indeed — because originally, Han, Finn, Rey and Chewie were unable to get into the one part of Starkiller base that really mattered.

“The oscillator is the only sensible target,” Finn told him. “But there’s no way to get inside.”

“There is a way.”

Everyone turned toward Rey. It was Chewie who ventured the question that had to be asked.

“I’ve seen inside these kinds of walls,” she told them as the sky overhead continued to rain destruction. “The mechanics and instrumentation are the same as the Star Destroyers I’ve spent years inside salvaging. Get me to a conventional junction station, I can get us in.”

19. Did Han and Chewie have a chance to say goodbye?

Sort of. Kleenex time again:

Unintentionally, their eyes met— and the stare held. Man and Wookiee realized it might be for the last time. Nothing more was said. Nothing more needed to be. There never had been, over the years, an excess of superficial chatter between the two whenever there was work to be done. Each knew his job and did it. That did not keep Han from pausing a moment to look back. When he did, he discovered Chewbacca gazing in his direction. Same ethic, different species, same thought, Han mused.

He pointed stiffly. “Go! Before things get messy.”

Chewie complied, this time without looking back. Han watched him for a long moment. Then he, too, turned and raced off.

20. How long had it been since Han had seen his son?

More than 13 years, it seems; maybe as many as 20. This snatch of description from their final confrontation says that Han has not seen the roughly 30-year-old Kylo Ren since he was a child:

Reaching up, he slowly removed the mask. For the first time Han saw the face of his son as a grown man — and it jolted him.

21. What was Ben feeling when he killed Han?

As befits the ambivalent character of Kylo Ren, there are two answers to this question. First, from Han's perspective:

Accepting without quite believing, Han stared back into the face of the creature that had been his son. There was nothing to see there. Only darkness in the shape of a face: alien, unthinking, unfeeling.

Then from Ben's perspective, which certainly seems to suggest he is no Resistance agent:

Stunned by his own action, Kylo Ren fell to his knees. Following through on the act ought to have made him stronger, a part of him believed. Instead, he found himself weakened.

22. Does Kylo Ren know something about Rey that she doesn't?

The fact that Rey is able to dislodge Luke's lightsaber from the snow before Kylo Ren certainly seems to confirm in his mind that she's someone in particular:

Rey appeared equally shocked that her reach for the device had exceeded his. She gazed down at the weapon now resting in her grip.

“It is you,” Ren murmured.

His words unsettled her: Not for the first time, he seemed to know more about her than she did about herself.

23. Was Rey ever tempted by the dark side?

Yes — when she had the opportunity to kill Kylo Ren, something she didn't seem to have in the movie:

"Kill him," a voice inside her head said. It was amorphous, unidentifiable, raw. Pure vengeful emotion. So easy, she told herself. So quick.

She recoiled from it. From the dark side.

24. How did General Hux and Kylo Ren escape Starkiller base?

This isn't seen in the film at all:

Utilizing the tiny position sensor emplaced in Ren’s belt, Hux had tracked him to this spot. He would have taken Rey and Finn, as well, if not for the command that had been issued by the Supreme Leader. That took precedence over everything. There was simply no time left. The two renegades were going to die here anyway, he told himself as he followed the troopers carrying Ren into the nearby shuttle.

25. What's the prognosis on Finn's wounds?

Pretty good:

When Dr. Kalonia finally emerged from the intensive care section, Rey nearly fainted at seeing the smile on her face. The physician’s words confirmed Rey’s hope. “Your friend’s going to be just fine.”

“Thank you.” It was all Rey could think of to say.

Kalonia looked down at her. “I don’t get to treat many lightsaber wounds. It’s such an old weapon. People today prefer to fight with rifles and blasters, from long range.” She shrugged. “I suppose it doesn’t matter. Death is death, no matter the mechanism that is employed to beget it.”

Her smile returned. “But not for your friend. Not this time.”

Still, Rey cautions herself later that "nothing certain could be said until Finn had fully recovered."

26. Did Rey and Poe ever meet?

Why yes, during the celebrations after the destruction of Starkiller. And it was kind of a meet-cute, possibly portending romance:

Rey and Poe were not excluded, though their sudden, tight clinch of shared excitement led to a moment of mutual awkwardness. “Uh, hi,” the pilot mumbled. “I’m Poe.”

She nodded slowly, searching his face and finding that she liked it. “I recognize the name. So you’re Poe. Poe Dameron, the X-wing pilot. I’m Rey.”

“I know.” He smiled back, a little more at ease. “Nice to meet you.”

27. Is there anything more we can learn about Luke?

Nope, sorry. The book refuses to offer any more details on the mysterious last Jedi. Here's how it ends:

Whether motivated by her stare or by something unknown, the figure finally turned toward her and pulled back his hood.

Luke Skywalker.

His hair and beard were white, and his countenance was haunted. He did not speak, nor did she.

Remembering, Rey reached into her pack and removed his lightsaber. Taking several steps forward, she held it out to him. An offer. A plea. The galaxy’s only hope.

She wondered what would happen next.