Well, if you choose a tank or healer you have a distinct advantage of never having to wait overly long for dungeon queue times since they're ALWAYS in demand. The big thing with those roles is learning dungeon layouts and boss fights to utilize proper mitigation. Far as your dps classes though, honestly try them all and see what feels right to you.

Far as your bard question: Yes they're DPS, but they support using their songs while dpsing at the same time

Best thing about this game is you don't need an alt so as said above, feel free to try as many jobs as you like