Re: Snape. I can, in the sober light of one year later, see a plausible argument that he's Dumbledore's man through and through (although I'm reserving judgment on whether I believe it), but my first answer was "none of the above." I think he's been serving the good side for the better part of six books, but that doesn't change the fact that he was always a man doing the right thing for the wrong reason, and I don't think this exactly makes him "good" in JKR's worldview. I also think there's a very good chance that he does fall under the spell of the Dark Arts once again during his term as DADA teacher.

Basically, I think he's the Dark Arts equivalent of a dry drunk, if that makes any sense.