I think one of the more mature and developed storylines in Rowling's series is the matter of death. She's mature enough to let a dead character remain dead(headmaster), and so I think she wouldn't revive someone like Sirius who has passed away in the fight for good.
I think that Snape is not evil. I think that Dumbledore planned his death so that Snape could appear truly evil and secretly fight Voldemort from the inside. Perhaps I only believe this theory because it's just barely possible, and it would be very entertaining and "twisty".
RAB is probably Regulus Black, although I loved coming up with theories like Roberta "Bertie" Botts.
I wouldn't mind Harry dying or living in the end. His destiny in the series leads me to believe that if he has to die, so be it for the good of all. It would also mirror Jesus' death and resurrection to save us all, so maybe more religious opposers of Harry Potter will lighten up. Probably not, but whatever, not everyone is Christian anyway. If he lives, I guess that would be happier, but if any of the students are going to die, I think it should be him. Someone like Ron or Luna or someone dying seems a bit out of the blue, and more unexpected and perhaps undeserved as characters.
Of all the possible people to die, I suspect Snape will, in his death attempt to save the wizarding world from Volemort. Now that's climactic!
As for the movies, I do not enjoy them as much as the books, and only really enjoyed PoZ and OotP. The others were okay, but only because I love the books, otherwise I probably wouldn't be so accepting. It would be like seeing Lord of the Rings, which I saw and barely enjoyed because of the special effects and epic battles.
My least favorite book was Chamber of Secrets, which lacked the excitement of a whole new world like the first book had, and because the greater scheme of things wasn't as prominent as it is in the more recent books what with Harry fighting for more than himself in a larger group of interesting wizard characters.
That's all I have to say for now, but I am keen to respond to others' posts. *APPARATE*