The Stories are from Harry's POV. Unless Rowling decides to start a chapter from another point of view, which she is quite good at doing.
As for order of the phoenix, Rowling said she had to get Harry to a lot of different places so she could lay down clues for the final book. She is aware of people disliking the book.
I can see the film being a thriller of the political and pyschological kind ie Harry dealing with Umbridge and the might of the ministry of magic behind her. Then he'll be dealing with flashes into Lord Voldemort's mind. It will have a very big but shocking twist at the end of the tale. I'm sure they will cut out as much of the book as they can. Rowling usually tells the screenwriter etc what neeRAB to be left in and what can be discarded.