Three dollars and some change

Well... there weren't enough options for me, so I answer like this :)

Morena Baccarin could do if the rest of the crew are taller enough... she has too dark skin, but I don't expect that there's too many actors who actually look like LKH describes Anita... Although I haven't seen her anywhere else than Firefly (where she is pretty much covered most of the time) so I don't know if she is athletic enough. Kate Beckinsale is likewise too tall, she just looks so nice in my icon :)
Nathan Fillion on the other hand doesn't fit my image of Richard at all, he's not... umm... beautiful enough. AB books are full of pretty boys and I just don't count Nathan Fillion as one of them. I like him well enough, but he's just not breathtaking.

I haven't seen that episode.

I don't think JKR is going to go there, but I've read a couple of fanfics where that's entirely plausible ;)

My OTP is Harry/Snape, but I chose the ones I like best from your list. I'm mostly slasher, Anita is one of the few women I can stand reading about enough to enjoy her in pairings :)

Alcohol and Ansku just doesn't mix well, I have abysmal tolerance for it and am drunk almost before I even start drinking... and I've done enough stupid and humiliating things while drunk that I haven't much touched anything stronger than water for years...