I definitely don't think Snape is bad - I wouldn't be surprised if he sacrifices his own life to save Harry's, therefore proving that Dumbledore was right to trust him. As for what else happens, my theories change daily! Today, I'm thinking that Ron, Hermione and Harry all survive but I think that's just wishful thinking! One of the Horcruxes, I'm sure, is the locket that was in Grimmauld Place because it was Sirius' brother that swapped the fake locket for the real horcrux one. I would think that Kreacher has it somewhere now. Oh, and I don't think Malfoy will turn out to be bad - we saw a whole different side to him in the last book.
As for what your friend said, it's just his/her theory - they couldn't actually know for sure. The Muggle world has gradually been becoming more caught up in the wizard world though so who knows? x