We will find out the reason why Voldemort killed Harry's parents.
Hermione will become a prefect.
Gryffindor wins the Quidditch cup.
Harry may go to live with Sirius Black.
The fifth book will be titled "Harry Potter and the Order of the Phoenix."
In book five, we go into a whole new area, physically, an area you've never seen before, a magical world Book five will be scary. Harry finds out a lot of things he hasn't stumbled across so far.
In book five (Harry) has to examine exactly what death means, in even closer ways.
We will see Mr. Weasley's car, Aragog, Dobby and the Dementors again.
Book 5 will be at least as long as Goblet of Fire! The Dursleys are in the next book, and there's stuff coming with them that people might not expect.
During an interview, when JKR was asked in which Hogwarts room she'd like to be for 1 hour, she said it would be a room in which Harry has been before, but doesn't know its importance. Yet.
It's very important in the plot that Harry has his mother's eyes, and that her wand was very good for charms.
During an interview for Kids BBC, Victor Greensteet (reporter) asked Rowling if Harry would have a dragon for a pet. This is what she replied: "You can't tame a dragon, no matter what Hagrid thinks. It's simply impossible. So no. He has more common sense. He MAY have a different pet in the future, but for now, I won't say anything else".
In the same interview for Kids BBC, the reporter asked J. K. if Harry had ever used the internet, and this is what she had to say: "No. They (the Dursleys) won't let him go near Dudley's computer, and Dudley is the only one who has a computer. They hit him if he gets too near to the keyboard. So the answer would be No. I use it a lot, but Harry doesn't. Wizards don't really need to go on the web. They have an even better way to find out what's happening in the outside world, which I think is a lot more fun than the Internet, but I'm going to keep quiet on this one."
The choice between what's right and what's easy will be a pillar of the plot in Harry's last 3 years.
The "Arabella Figg" Dumbledore refers to at the end of book four is indeed the same Mrs. Figg that takes care of Harry for the Dursleys in book one.
There will be a new sorting hat song.
You'll be seeing Mrs. (Arabella) Figg in book five, and you'll find out all about her.
Harry's parents' profession will be a big part of the plot.
Harry will see the real 'Mad-Eye' Moody in book five. We will find out why Voldemort killed Lily and James Potter.
Something HUGE will be revealed about Lily Potter.
There will be a female Defense Against The Dark Arts teacher (*coughMRSFIGGcough*)
We'll see Lupin in Book Five. Yes, we will see a lot of old characters in Book Five.
Ginny Weasley will play more of a role in book five.
One of the main characters, one of Harry's "fans" will die (not Ron or Hermione though). The death will be "horrible to write."