sorry for going backwards, but do we know that a Weasley is going to die?
if so i think it will either be Bill, Charlie or maybe Percy
Bill - i dont really believe in that almost-death-situation-in-the-past-vaccination. and in book 6 we got to know him a bit better - just enough for us to get to know him better in 7 and then for his death to have an impact (especially seeing as he'll get married in the beginning of the book)
Charlie - i think they always mention him in the earlier books as very successful and good so maybe he'll do something big for the order. besides that's the one weasley we know the least about and havent even heard speak if i'm not wrong...
Percy - i think he's gonna live cuz it's a way for her to show things about people - about ego, and stubburness and maybe in 7 about getting over these things. i think that if he dies he will not reconcile with his family before.
Ron (just as Herm`) will stay to the end, Ginny's death will be too hard and painfull.
the twins won't die cuz we need them for the comic relieve and they go together - if one dies it'll be ruined
and on to other people - i think there'll be a death of someone close in the beginning, and then maybe a scene of a big fight in which several people from the order will die. about the first death it occured to me sadly that it might be Hagrid - we had several opportunities to see that he's really very strong - also against magic so him dying in a fight or an ambush by the DEs will be quite a surprise and he's exactly the - very good friend but not vital to the cause (sorry for the coldness) - kind of charachter