With the signing of Gaffney we are absolutely LOADED at WR.  Who do you think will win out?  I'm thinking we roll with seven WR, four RB, and eight OL. Here's what I think the competition looks like.

Return Skills will win it (2-pick one): Edelman and Jeremy Ebert (similar players)

I actually think it may come down to an either/or between Branch and Gaffney with Gaffney winning out because he is younger and has the two year deal. They both fill the TB's favorite receiver role, but are rather similar in skills. The rest of your analysis I agree with.

Safe: Welker, Lloyd (unless he really doesn't get the system)

Slater is not gonna be a WR with gaffney coming back.

Like to see Ebert make the team, the kid hustles like WW

Hey Wes,
Come back soonest!! We luv ya!!! 9M+ ain't bad...

I agree that Slater won't see time at WR, but I think that he'll get one of the WR spots.  I like Ebert because it'll be nice to have some young legs with all the veterans on the team.  Plus, a rookie like Ebert is far cheaper than somebody like Stallworth, Gonzalez, and Ocho.  At the #4/5/6 spot, I think BB will go with the cheaper rookie, knowing he'll get about equal production from Ebert as he would from Gonzalez, Stallworth, or Ochocinco.

I guess I wouldn't say we're "loaded" at WR. Yeah, there are a lot of guys on the roster right now (12 by my count), but I'm not sure there are a lot of quality guys. I think wideout has been a relatively weak position for us for a while and BB is clearly trying to address that weakness by bringing in as many free agents as possible to increase the level of competition. I think it's very hard to say right now who will make the team because a lot of these guys are aging and on the downside of their career, so past performance isn't necessarily a predictor of future performance. How they perform in camp and in the preseason is going to be crucial. I also wouldn't be surprised if BB also brings in one or more rookie free agents to see if he can find a (young) diamond in the rough.  

I think Slater may get moved full time to FS - he hasn't shown much at WR so why not - ultimately he makes the team (or doesn't) because of ST.
I also wouldn't count out either Davis or Underwood - they are basically rookies as they haven't had an off season with the club. David is 6'3" and ran 4.5. Underwood is 6'1" and ran 4.31 with a 41" vertical! And if Gonzalez is actually healthy he is the youngest 'experienced' receiver.
This is going to be wild competition in camp, discounting the possibility of a few more bodies coming through as well.
And it isn't just WR - DLine, LB, and DB all have a bunch of bodies with various skill sets and experience. OLine is the most 'set' group, and even there some new back-ups may stick.