Your first 3 are spot on. But for the 4th most likely Krejci. Any other year I would have said Zajac cause he was getting better and better every year until last year, but then again, the entire Jersey team struggled.
Unless you feel you want to keep at least 1 D, then Ehrhoff would be the guy. But after being traded, it's hard to say he'll perform the same way in Buffalo.