I think that Dumbledore is dead. I agree about the funeral being too final, too serious for Jo to not be serious. And while we're speculating about Book 7....
I do believe that Snape was meant to kill Dumbledore, and Dumbledore wanted him too. Remember the conversation in the forest that Hagrid overheard? Dumbledore was saying that Snape had promised to do something, and Snape was questioning it, thinking that Dumbledore was "assuming too much." I think Dumbledore knew that his death was part of the greater scheme of things, and perhaps would be the cause of something good. I just know that Dumbledore would not have let Draco's plans go through unchallenged if there weren't a reason Dumbledore should die. DUmbledore made it very clear at the end of HBP that he knew what Draco was doing all along, and he knew about Snape's Unbreakable Vow. Yet he allowed both people to be in the castle.
Also, I know that Snape is trustworthy. Rowling said that Dumbledore was never very far wide of the mark, and I believe that if Snape was not trustworthy she would not have said this. That would be an assumption very far wide of the mark; to falsely trust your own killer! I believe he knew Snape would end up killing him, and had planned it that way from the beginning.
About Harry being a Horcrux, or his scar being a Horcrux...Based on what JK has said, that Dumbledore is never very far from the truth, his scar really is just that; a scar from the killing curse. I know everyone says "It doesn't leave a marK!" But Dumbledore said in response to that that the killing curse does not usually leave a mark, however the exception is "sitting before me." Harry was, of course, sitting before Dumbledore. Also, the six horcruxes, and Voldemort's soul in his body, are pretty well known. I do not think Dumbledore's guesses were wrong, but he was vague about a relic of Ravenclaw's or Griffindor's. Some say that Harry is a relic of Griffindor, but I think not. He may be related (ie Godric's Hollow) but the idea of putting a Horcrux in Harry presents too many obstacles: "Can a person be killed, then imparted with a Horcrux? Wouldn't killing Harry destroy the soul piece by causing it to flee Harry's body (which is exactly what the Killing Curse does)? It was "mortally painful" for Voldemort to enter Harry's mind, even with Harry's blood. So how would his soul survive being imparted onto Harry?
Anyways, I'm rambling, tell me what you think. And please, challenge it if you have evidence.