Who did Rowling give confidental information to about future plots?

Question

Was the casting of Alan Rickman as Snape based on the full knowledge of the future of that character? points out that J. K. Rowling gave some information to the actors of Hagrid and Professor Snape about the plots of future books of the Harry Potter series, in order that they can act their roles better. Quoting the interview from 2001

Lizo: It's been reported that you talked about the "back story" of some of the characters with some of the actors. Is that true?

JK: I'm very secretive about these things, but yes I did. I gave certain people certain information. I gave Robbie Coltrane some background on Hagrid, which I think he used superbly, because I think he's an absolutely fantastic Hagrid.

I also gave Alan Rickman a little bit on Snape.

To which people did Rowling give such secret information about the plot of books before they were published? If it's known, I'd also like to hear when (before which book) they spoke with them, the purpose why they chose that particular person, and what she told them. I'm interested only in information given in private to very few individuals, not information in public interviews or similar.

Answer 1

The three lead actors were told certain things

Meredith Vieira: Do they know what hap-- did they know before this book came out?
J.K. Rowling: They knew certain things. I mean, none of them knew the ending. But-- I told all three of them stuff about their own characters.
Meredith Vieira: Did any of them ask, "Are you going to off me?"
J.K. Rowling: Yeah, Dan did, yeah.
Meredith Vieira: Daniel did? And did you tell him?
J.K. Rowling: I took him out to dinner … And at one point during dinner, he leaned in and he said, "Look, I've got— I've just got to ask you— do I die?" And I thought quick and then I whispered, so no one else could hear, you— you get a death scene. But Dan is very smart. And I'm pretty sure he would have walked away from that dinner thinking, "Yeah, I get a death scene, but what does that mean?" (LAUGHTER) — he dies. So I hope he's happy.
Meredith Vieira: Yeah, it is his career after all. (LAUGHTER)

_{"Harry Potter: The Final Chapter - NBC Dateline, July 29, 2007}