I don't think that Dumbledore is dead. I think that he staged his death, and froze Harry as a witness, unable to interfere. He needed the world to really believe that he was dead. They now do. Also, it forces Harry to act. Harry must now take the battle to Voldemort. No more childish fancies.
Dumbledore is now far more free to search for the 4 Horcrux and to prepare for the battle with Voldemort. So are Harry, Ron and Hermione.
As for Snape, he was obviously in on the staged death, hence is still a good guy. He protected Draco by both "killing" Dumbledore (Draco's task, set by Voldemort) and by getting him out of Hogwarts. This fulfilled his unbreakable vow to Draco's mother. Snape is on to the next task set by Dumbledore.
He didn't kill Harry on the grounds, nor did he allow others to kill Harry when they had the chance. He is clearly a good guy.
As for R. A. B. - no idea ----yet...