Originally Posted by
Tokitoki
You should take a look at one of the many FFXIV wikis. This game's structure is wholly different from XI.
All the significant PT mechanics are within instanced dungeons or Primal (Avatar) encounter arenas. These are usually matched through the Duty Finder utility that automatically puts together your PT with 1 tank, 1 healer, 2 DPS. The 2 DPS can be any of the DD jobs, this includes BLM. Any tank or healer job will get a party quickly through the duty finder (usually) simply because there are less healer and tanks than DPS.
As far as end game goes, PLDs right now are at the bottom of the tank rankings. BLMs are also generally near the bottom of the DPS rankings along with MCH and BRD I believe. That doesn't mean they won't be adjusted at some point, but at this point in time WAR is the top tank and SMN seems to be the top DPS.
AS far as servers, there are so damn many it doesn't really matter which one you choose. Each server is placed in a cluster and that cluster is where the Duty Finder pulls people from. You'll be playing with people across 3 or so servers I think it is.