1. It's a bit of a stretch, but considering that Yukari Nakano (who surely would have been ahead of both Flatt and Csizny) will not be there and Sarah Meier most likely won't be in top condition, it's not as impossible as I once thought it would be. I don't think either will be top 4, but both have reasonable chances for top 10, so it could happen.
2. Well as you said, we haven't watched the Men since Worlds hasn't happened yet, and Johnny hasn't competed since Nationals. But since he has the habit of not maxing out his programs, I don't think he would have changed that much. I do think he would help to guarantee 3 spots for the US men, but I feel fairly confident that this team will do the same just fine.
3. Joesitz, you've been very hard on M/B lately it seems. They're still a very young team prone to making silly mistakes as they develop and mature. Also, Rockne has had blade troubles this season. Though I think D/B skated cleaner at Nationals, M/B seemed a lot more polished and I do think the results will come with more time (the international pairs field has gotten a lot more competitive IMO, so you can't reasonably expect to start winning and medalling immediately). But they did finish pretty close to each other at 4CC.
4. I don't know that D/W are considered the #1. Certainly they have a lot of momentum; medaling at GPF, winning Nationals as well as 4CCs. But B/A are the current Olympic silver medalists, 5 time National Champions, and 3 time World medalists among other notables. Beside that, they are making strides in improving their skating. Despite my bias for D/W I see these teams as being very close; Worlds will tell part of the story, but not all of it. As both continue to improve (as we know B/A will, but will Igor emphasize what D/W need?) I think they'll stay close. Right now it isn't quite clear because we haven't seen B/A since GPF, but they were ahead of D/W by about 2 points after the OD. It'll be interesting to see.
There are other countries with a lot on the line. Canada is looking for three spots in all disciplines (and if V/M end up withdrawing they could only have one ice dance spot). France is hoping for three spots in mens and ice dance. Russia is looking for spots, and I'm hoping that Tomas Verner skates well enough to secure a spot for Michal Brezina.