about the queues are mentioned above, nicely in details so I want to say just a couple of things about the main class

4. BRD class - I'd suggest you to play the class you prefer, but you should try many class as you can since learning to play the others' role make you do the job better, in my case, healer who know how to control mobs aggro make tank's job easier. speaking of maining BRD, BRD is capable of keeping stable damage (since BRD can keep attacking while running and the range is insane), due to this advantages. BRDs are often put to deal with boss mechanics. To put it simple, if you're good with multi-tasking stuffs, people will be chasing after you.

5. Race : not really effect the end-game content, if people can do their job properly, that 1% difference doesn't matter at all so don't worry
Multi class : stats in this game depends on gears with 30 bonus stat, that 30 bonus point is seperated by class.

hope this help!
have fun playing FFXIV