I haven't been around in a while, but I will try to check in and answer any question one might have about the WBC.
The A&A event is played with Revised and a modified VC scoring sytem:http://www.boardgamers.org/yearbkex11/a&apge.htm
There was actually a GTO player that came in third last year:http://www.boardgamers.org/yearbook/a&apge.htm
I talked to him briefly after the event (since I wasn't there for the tourney, it is now a Pre-Con) but I don't remember his GTO nickname.
Understand that there are certain major differences between playing here and playing in a ftf tournament.
1) Game time limits- The games are limited to 4.5 hours. It can end sooner if you reach the automatic win conditions or your opponent concedes, but with good players the games normally go the full time. The corollary of this is the need for the players to keep the game moving so that a reasonable number of game rounds are played during that time. I would generally implore the participants to get in a minimum of 5 rounds.
2) The VT Scoring System- The scoring system used at WBC is a modified VC system that I came up with because of my dislike for the OotB VCs. The current GM continues to use this system.
3) A lot of A&A in a short timeframe- This isn't usually an issue with hardcore players, but you are guaranteed (if you want) to play at least three games, and if you advance into the single-elim rounds you could be playing a full five rounds. Two on Saturday and then three on Sunday. It may not seem like a lot but that second day can be a really wear you down.
Does GMing prohibit you from being part of a team competition?
Because GMs are volunteers, they don't put restriction on participation. I personally chose not to participate in the A&A event while GMing (except to fill in if there was an odd number) only because I had a lot of paperwork to do and rules questions to answer while running the event.
While you can play in and even choose the event that you are GMing to be your team event, I would think that that would seem a bit weird. While the quality of the GM is very high at WBC, some may still look at such a situation as a little off. You would have to have earned a good reputation to ward off the speculation of the players, especially newbies who might think that this is some kind of inside fix going on.
WBC is a quality event in the main part because of the convention staff and the volunteer GMs. They do a fantastic job of keeping the focus on a certain number of good event instead of a free-for-all convention like Origins or Gen Con.
To balance that, they have worked hard to give the attendees an amazing open gaming room that includes a vast game library for one to check out and play new games. Plus, there are always people looking to play just about any game you can think of.