you aren't told, but he does fight in the battle of hogwarts
She doesn't.
No,he graduates.
No, she survived.
Yes, Dumbledore is killed by Snape in Harry Potter and the Half-Blood Prince.
No, Dean Thomas doesn't die in harry potter. Although many loved characters do: Dumbledore, Dobby, Snape, Fred, Tonks, Lupin, Colin Creevy, George's Ear and many more. RIP