Question: Why do Chris and her friends bully Carrie? She's never done anything to them and I've read the book which also provides no answers.
Answer: Bullying doesn't have anything to do with whether or not someone did anything to someone else. Bullies zero in on people they know are emotionally weaker and less able to defend themselves. Carrie was extremely shy, awkward, naive, etc. These are traits that bullies tend to exploit for their own amusement and to make themselves feel superior.
Question: In the beginning of the movie after Carrie goes home after starting her period, her mother starts reading from something about God cursing Eve with blood and the first sin was intercourse. Does anybody know what she was reading from? I can't find it in the Bible, and it doesn't look like that's the kind of book she was holding.
Answer: It seems completely made up for the movie, especially the line "the raven was called sin." In the movie she's holding what looks to be a religious pamphlet, but it's not anything from a real book. In the remake of the film, after her mother says "the curse was the curse of blood", Carrie adds "that's not even in the Bible."
Answer: I took it to be a reference to the Serpent Seed doctrine. Proponents of the Serpent Seed doctrine believe that the Hebrew and Greek words for "deceived" when describing the story of the first sin actually literally translate to "wholly seduce" (They don't). The doctrine goes that the Tree of Knowledge of Good and Evil was actually Satan himself, and that "eating the forbidden fruit" is actually a metaphor for having sex with Satan. The doctrine continues with the claim that Eve's son Cain was actually the spawn of Satan, and that descendants of Cain actually survived the Great Flood and are still among us to this day. The Serpent Seed doctrine has been debunked by many scholars, and there is no evidence from the text of the Bible that it is true, but there are still a lot of religious extremists that believe it.
Question: Why did they change her name from Rita Desjardin, in the book, to Miss Collins?
Answer: The only answer I could find online was that it was changed simply because "Miss Collins" was easier to pronounce/remember. It's also worth noting that it's really not all that uncommon for movie adaptations to alter and rename characters. Especially supporting characters. Given there are some other changes to the character in the movie, renaming her could have also been a way to distance her more from the character in the original book.
Answer: That was always the impression I got until the sequel was released in 1999 (The Rage: Carrie 2) that made it clear Carrie White was definitively dead.
BaconIsMyBFF
So her grabbing her arm, what was the purpose for that?
It was a nightmare, never happened, it was just Sue's imagination.