from the peanut gallery...
1: ever since he 'died' he's had the ability.. I seem to recall it being told that he died, but remains cause he's got something left to do... and the eye-thing was just an extension of that. since he's dead, he can see the death of everyone and everything else too.
though as always, I may be massively WRONG in this... *shrugs* don't bother pointing out how to me.
2: yeah, just a random character.. the hentai game has her in a few positions (if I mean sexual ones, or positions in the script, I'll let you decide on your own *grins*)
3: since she came back after Shiki killed her, supposedly in much the same way Roa did, I suppose it's possible that she's not dead.
and she didn't turn to ash so much as she simply faded.
course, so did Roa.. and Roa had to reincarnate everytime that happened to him... and the way they talk about it, that was something special to him.
though... frankly... and for me this is the bottom-line, when she returns to say 'bai bai' to Shiki, it doesn't feel like your ordinary dream-sequence... but as if she's really there. so I'd say, she's alive... but doing her own thing.