A good friend of mine read through the novelization and developed a list of some solid revelations from the book that answer a load of questions the movie doesn't really answer well, but beware this list is a bit long:
- Lor San Tekka (Max Von Sydow's character in the opening scene on Jakku) is a "great solider of fortune". Tekka dismisses Poe with the knowledge that Tekka will soon be dead. Tekka's dialog with Ren is a genuine attempt to bring Ren back to light.
- Ren is more philosophical, abstract, and eloquent than his dialog in the movie indicates. His subsequent dialogs show an incredible amount of conceit / narcissism.
- Finn tries to play off his not-shooting the villagers as a blaster jam.
- When Rey rescues BB-8, it's driven by the Teedo insulting her with vulgarity, as well as being the right thing to do.
- When Rey tells BB-8 that she's waiting for her family to come back, she does so through masked tears.
- Rey actually counters Plutt's offer of 60 portions with 100 portions. Plutt agrees, and Rey ACCEPTS the 100 portions, before having a crisis of conscience that rejects Plutt's offer.
- Hux is worried that Finn's treason suggests that others in the ranks might harbor the same sentiment.
- While this is explicitly mentioned in the movie, concurrent dialog masks it: Rey mentions that she's flown lots of ships in the past, which is why she was able to fly the Falcon. In the book, she indicates shortly after this that at night, she'd poke around all the ships parked at the outpost to learn about them.
- When Ren learns that "a girl" helped BB-8 escape, it seems like he's afraid that the girl might be someone he knows. This tone is echoed later as well.
- Leia (and 3PO) has been keeping tabs on Poe and BB-8 the whole time. They knew about the destroyed X-Wing, but found no evidence of BB-8 wreckage. 3PO conceived of instructing Resistance-friendly droids to alert them on seeing BB-8. Hence the droid in Maz' cantina that signals the Resistance.
- Leia sends a delegate to the Hosnian system to emplore the Senate to take action against the First Order. This is the woman on the balcony in the movie who sees the sky turning orange right before her planet is destroyed.
- Snoke's philosophical motivation is essentially ancient Greek Stoicism - rejecting subjectivity and emotions in favor of logic and tangible, real things. Snoke blames the fall of the Empire on Vader having a failure of character - sentiment.
- Poe wakes up in the desert, and has a fun scene getting a lift to a nearby town, displaying further prowess as a tactician and pilot.
- When Rey first lands outside Maz' cantina, she's stunned by the smell of the planet. Han explains that she's never smelled so much oxygen before.
- Plutt tracked the Falcon to Maz' cantina, and arrives to take it back from Rey. He gets rough with her and she tries to shoot him with her new blaster. Plutt yanks the blaster out of her hands, and condescendingly explains that she needed to take the safety off. At this point, Chewie shows up and yanks the blaster out of Plutt's hands, and subsequently yanks Plutt's arm off.
- During Rey's vision, there's a boy at the end of the hallway (it's not clear if this is the Cloud City hallway, or some other hallway). When she hears a voice, it's known to her (it's not clear if the voice is Luke, Ben, Yoda, Ren, or what...).
- When Rey and Ren meet in the forest, their dialog is more philosophical. He essentially argues that her desire to kill him is out of ignorance, which is simply remedied. He has some ethical banter with her, and then seems to recognize who she is, but can't place it.
- BB-8 tracks the ships direction after they leave the atmosphere. Perhaps this is how Finn is positive where Ren took Rey.
- Maz survives the whole conflict, and tells Finn that she seems something different in his eyes now - the eyes of a warrior.
- During Han & Leia's dialog about Ren, Leia indicates that she'd known that Snoke posed a threat to their son since he was born. This indicates that Snoke has been around for a while, and is well-known to the Resistance. Further, she takes more of the blame for Ren than in the movie, because she kept this information from Han. She ultimately was afraid that Han wouldn't have the patience and understanding to handle it right.
- When Ren is interrogating Rey, he unlocks her bindings with a force gesture, and locks them back as he leaves.
- When Ren is trying to read Rey's mind, he encounters a barrier. The way this is written doesn't indicate that the barrier IS Rey - its ambiguity might imply that the barrier was placed there by some other means. It's also stated more explicitly that SHE got into Ren's mind, and had acquired knowledge from him.
- Snoke is terrified that Skywalker will return to the Resistance to challenge their power.
- Rey and Finn take a dangerous snowspeeder ride to a spot to unlock the doors that Han & Chewie go through before mining the columns of Starkiller Base.
- When Chewie and Han split up, they share a lingering "good luck" look that is heavy with foreshadowing.
- After Ren kills Han, he's stunned by his own action, and that the act didn't make him stronger.
- When Ren duels with Rey, he finally recognizes her (it's not clear what this means, but it's clear that he recognizes her). During the fight, her rage and fury are referred to several times. When Ren is on the ground, a vengeful voice in her head tells her to kill him. She recoils from this voice, and explicitly from the dark side.
- The stairs on the island where Rey finds Luke had been worn through thousands of years of use.