Harry Potter and the Order of the Phoenix (SPOILERS)

[Babette]

I read the first 4 books before seeing any of those films, but never read #5. I saw Order of the Phoenix Sunday and I enjoyed it. I was confused in some parts, so I am now reading the book to fill in the blanks.

*How did the dementors get there?
*Why does Voldemort want the prophecy? What is it?
*Who is the awesome character played by Helena Bonham Carter?
*Where were they and where did all of those vaporous characters and archway come from?
*I knew Ron would grow up HOT!

I avoided this thread until I saw movie #5, knowing it would have spoilers from movie/book #5. I agree with the please do not spoil #6 & #7 seeing as how many people have posted in this thread that they have not read the books and like to enjoy the movies. I understand that in HP circles people have read the books, but this thread is different types of people discussing a movie, not just diehard HP enthusists. Heck, I just learned about the big spoiler in #6 a couple of days ago!

I like when a movie adaptation uses the base of a book, but modifies it for the screen. I have only read 9 of the 38 chapters of Order and they are still not even to Hogwarts. Something had to be cut, but maybe a little too much important transition/linking plot was cut for the non-book reader to follow.

Why does every HP book have to span the whole school year? Are Voldemort and his followers only able to "attack" just before summer holiday?