Q:
What Server?
As far as I know the only way to tell is to log on.
You can tell which one you picked by the world selection tab on the log in screen. There will be a little house by your home server ( the one you chose) You cannot change servers without paying and all your characters belong to that server. As far as I can tell all the servers are pretty healthy as far as population. I am on stormbluff isle and I like it and would recommend it.
You dont even need to look at world selection tab. The information to the left of your character in character selection screen shows which world (server) you represent, along with your present location, profession, etc.
Well if you want to do it the easy way :P