Of Harry Potter and the Half Blood Prince she says, "It is a time for answers, not more questions and clues, although obviously there are a few clues as I am not qhite finished yet. I hope that that is sufficiently frustrating for you, knowing that you can't read it yet."
She talks about the difficulty of separating the characters from the actors playing them in the movies. She says:
"I make this hero--Harry obviously--and there he is on the screen the perfect Harry, because Dan is very much how I imagine Harry, but who does every girl under 15 fall in love with? Tom Felton as Draco Malfoy. Girls, stop going for the bad guy. Go for a nice man in the first place. It took me 35 years to learn that, but I am giving you that nugget free, right now, at the beginning of your love lives."
She spoke at length about the character Rita Skeeter, the journalist and the Thestrals. Rowling gives some tantalizing clues in her answers. Hmmm...the barman at Hog's Head, Dumbledore's brother?? Dumbledore's patronus, the backstory on the paintings at Hogsworth, Gilderoy Lockheart is based on a real person, the events surrounding Harry's christening, Dudley... Read the whole thing at her website. Great questions, fun answers, now I have MORE to think about.