But that's just it - the Xaela tribes have such a huge amount of variety to them that no single class best suits them as a race. You have one whose females are explicitly archers, ones that are more into hunting and gathering, several which are hardened and vicious warriors, and still others that prefer to keep entirely to themselves. You have a lot of freedom to play around with, here, and without knowing more about the background of your character, it's tough to say which class/Job suits them best lore-wise.

As for city-state, it's true that Limsa is the rough-and-tumble melting pot of the three City States, but it's also debatable how accessible it is from Othard, since Limsa is off the west coast of Aldenard and there's ostensibly an entire New World continent between it and Othard's east coast. As such, it may be more realistic for somebody from Othard to arrive in southeast Thanalan; indeed, this is precisely where the Doman refugees came ashore. Unless your character has specific business or training to seek out in Limsa Lominsa or Gridania (see above re: archers), I'd say Ul'Dah actually makes the most sense as a place to start for a Xaela character.