No, it's not that kind of job. It's more like a type of fighter. You can choose between White Mage, Black Mage, Thief and so on. This will decide your actions in battle. It's probably easiest to be a Warrior in the beginning, though. Since he's the strongest.

Ok, the moogle house in Bastok is nearby the Auction House. There's one Auction House in the "Bastok Mines" part of town, and there's also a moogle house nearby the other auction house in the middle of Bastok. If you don't find it, just ask someone nearby, I'm sure they'll help.

(you can also sell stuff at the auction house btw.)