As part of transition to 2.0 you might be given a chance to change GCs (given you'll be able to change race and appearance and all), but that would probably be a one-time deal.

And nothing ever required you to join the Flames and start in Ul'Dah to get all of the community support that is in Ul'Dah, you'll just have to go over there to shop of whatever.
I admit I started in Ul'Dah and joined the Flames only because I really liked the cty and I think it's the Eorzean version of Vegas. But you could totally be a gridanian aligned with the Maelstrom and get pretty much all the support that the community offers in Ul'Dah, you'd just need to travel a bit more.