Ooh - yeh I agree. I think it's too obvious to have Snape as a proper bad guy - so I think he's just being a complicated double-crosser. At least I hope so.
But I don't think Dumbledore will come back (apologies if anyone didn't know what happened yet!)

There's a lot from Lord of the Rings there too - the enchanted forest with all the weird trees and stuff, the Dementors are blatently the Black Riders, Dumbledore is Gandalf (and Gandalf came back so maybe you're right MMario)... etc etc...

xLx