Back to the death thing - if we're speaking about a Weasley having to die, then I truly believe it might be one of the twins. I have no real logic for this except for the fact that they are very close (I believe the parallels with Padfoot&Prongs are deliberate) and very obvious. I don't know how one would die, but I believe that a twin dying (possibly George?) would be far more tragic and bittersweet than Percy dying. There's also the fact that whilst Molly is worried about Percy, Bill and maybe even Charlie, she's not worried about the twins. The fact that she practically ignores them - "That's everyone in the family!" - is a warning sign to me. Of course, we've already had her regretting being nasty to them in GoF - but I still think that one of them might die.
Holy freaking crap, people. I can't believe it.