Good post.
Here's my take on those spots:
QB3: Yeah, I don't see us having a 3rd QB on the roster this year either.
WR3: Like some others here, I don't really see a clear cut winner of this spot. I think both Harris and Williams play a good bit depending on the situation. Williams will line up outside if Dez or Austin can't play for some reason, and when he plays as a 3rd WR with them, then Austin will get kicked inside to the slot where he has always been effective. Harris, on the other hand, is truly a slot receiver and Austin will stay outside when he comes in. I can see situations where the team might want Williams outside and Austin inside - and I can see it the other way around too. If Williams is as good as the team thinks, then he gives the team a ton of versatility and depth. Really a good pick by Dallas.
WR5: Here, I might as well flip a coin. The team could go with either Beasley or Coale... or someone else for that matter. I don't think Coale's draft position affords him any edge in this battle. IMO, he will have to win the spot outright in order to push Beasley off the squad. In other words, I think this is a true camp battle where the winner stays and the loser is off the 53.
RB3: If I had to pick a guy right now it would be Dunbar. The team really liked what he did last year and they love his athleticism. My personal favorite is Tanner. He has toughness and strength, and is a stocky guy who is difficult to bring down. Murray and Randle are longer, leaner types and I feel like Tanner is a different kind of back that can compliment the two guys in front of him. Plus Tanner, by all accounts, has had a terrific offseason and is faster and in better shape than ever. He also is a Garrett RKG, who loves the game and competes his butt off.
TE2: While most seem to think that Hannah will see a larger amount of playing time than Escobar, I kind of see it the other way around. The rookie has fantastic hands and is one of the more fluid pass catchers I've seen at the TE position coming out of college. The ability to naturally pluck the ball out of the air can be worked on, but IMO it is really something that you are either born with or your not. Gavin Escobar was born with it. Running fast, and jumping high is great, but the main thing a 2nd TE will be asked to do in Dallas is catch the ball... and Escobar is really, really good at that. That isn't to say that I don't like Hannah. I do. A lot. He is one of the better athletes at the position in the NFL and frankly, I'm surprised that he lasted as long as he did in the draft. He can stretch the field like a WR and he will just kill LB's who are asked to cover him. I do think that both Hannah and Escobar will play a good bit, but I think Escobar becomes a dependable threat for Romo to (finally) have out of the #2 TE spot.
TE4/FB: I agree. Rosario.
RT: I think Free keeps his starting spot. I don't think he's nearly as bad as he seemed last year, and I think getting used to Callahan's system will be a huge plus for him. The switch from LT to RT and from Houck's system to Callahan's system just killed his performance last year. By the end of last year he was playing much better and that should continue on into this year.
C: Like you, I think that Costa's surprising solid play last year and at the end of 2011 is indicative of what we really have: a solid starting center. And I kind of feel like getting the best 5 guys out there will take putting Frederick at G and Costa at center. However, I really think the team is going to put Frederick at C and just leave him there... and maybe that really is the best thing to do. Center is an important position and most good teams always seem to have a better than average center more often than not. Callahan in particular feels that C play is crucial to the success of the line as a whole, so putting a big, smart, tough first round pick at C really might be the smart thing. I certainly won't be upset if they keep Frederick at the pivot spot, and I think the guy will be very, very good there.
OG: I think Bern wins one spot and the other will be between Leary and Livings. I hope Leary shows enough to win the spot, and I think he will, but even with Livings, the interior line play should be much improved from having Frederick at C instead of some 4th string guy we brought in at the last second. Not to mention that continuity along the line (health) and another year in the new system should account for a big improvement inside.
OG3/4/5: I see Arkin getting one final year, the loser of the Leary/Livings battle and Killer K.
DL: I see a starting line up of: Ware, Ratliff, Hatcher, and Spencer. I think Crawford will see time at SDE when Spencer needs a break or when we need to go big, and I also see him getting some snaps in passing situations at the 3-tech DT spot. IMO Crawford is an important rotational player who offers a ton of versatility. If Ware needs a breather, then we could move Spencer over to WDE and bring in Crawford at SDE. He just offers all kind of possibilities along the DL. Lissemore, Bass, Wilbur are the rest there with Hayden having an outside shot.
LB4/5/6: I think Holloman and Magee are almost locks to make the roster. They offer a ton on special teams, don't cost much, and are ideal for Kiffin's LB positions. Albright is a Jack-of-all-trades who the team likes a lot, so I think he sticks as a backup SOLB/DE. Despite being the RKG, I don't see McSurdy making it this year. Coming off an achillies and really not having the athleticism for this defense is just too much to overcome IMO. Sims fits the defense to a tee, yet he has had concussion problems, so I think his spot on the team is in jeopardy... but I can see him sticking around because he played so solidly last year in a defense that didn't fit him nearly as well as this one.
S1/2: I see Church at SS and Matt Johnson at FS. IMO, that is a very solid safety combo. Big hitters, smart, and Johnson has a nose for the ball. Wilcox is the wildcard here. He is so physical, and so natural in coverage, and Kiffin's safety positions are so easy to learn that I think there is an outside chance that he wins a spot this year. More likely, he plays a good bit in sub packages while Johnson and Church start. Add in the experience of Allen and I am really excited about the safety position for the first time since the real Roy Williams. I think we have some damn good players there who will very quickly become household names. I think there is an outside chance that Hamilton either knocks Allen completely off the team or that he makes the team keep a 5th safety. He is very talented and Kiffin really likes young safeties who fly around out there.
CB5/S5: I think you nailed it here. Moore should stick as a do it all DB.