Great post, makes it real easy to search. And yes Leonidas, this list does reflect the CBA rules for FAs which is why you see so many RFAs on it.
In terms of UFAs, we have to remember that Nix said that he wants to build through the draft so do not expect big name free agent signings. I'm also going to initially assume we stick with the 4-3. So with that in mind, my realistic outlook on FA is:
Kevin Walter, WR from the Texans (6'3 but really shifty, would complement Evans very well)
Levi Jones, OT from the Redskins (We should have done this last year, he really started to come in during the last 8 games of the season)
Artis Hicks, OT from Vikings (Not really well known, but he's been in the league awhile and has some starts under his belt at both OT and OG. Good depth and insurance in case Wood can't make it back)
Dwan Edwards, DE from Baltimore (Finally got a chance to start and proved what a good run stuffer he is...not much of a pass rusher though so hopefully Schobel stays on for one more year)
Tully Banta-Cain, OLB from Patriots (Even if we do stick with a 4-3, I feel like he's got the speed to play OLB and is still an upgrade over Ellison).
Obviously that list changes dramatically if we go to a 3-4 (which there seems to be a lot more UFA options for). We'll know in a week I suppose! Plus, I truly believe the Bills will trade for a QB during the offseason.