I don't think Snape will be bad.He's unlikable but not evil. There are a few reasons why I think this, one don't think it's enough of a reveal. We've been allowed to see Snape in a sympathic light (e.g him getting bullied by Harry's Dad) and I think most importantly Dumbledore trusted him. Dumbledore has consistantly been he savour of the books. Dumbledore knows everything and is never wrong. If Dumbledore believed in Snape it will be for good reason.

I think Harry might die, I agree with Buzz that He will kill Voldemort using love and compassion.But I think that Harry will give his own life to save that of his friends, it will bit some lark about, making the ultimate sacrifice in the name of love being the most powerfull magic of all. The same thing that his mother did for him.