Yes, the limitation is your slots for new toons. 2 for F2P, 4 I think for membership and you can buy more slots with DBC, I think. Hope that helps.
Okay, I just couldn't remember if it was allowed. I'm probably going to upgrade from F2P as soon as I can figure out how to pay for it.
Thurgadin is a different region as is Test, so you can have the same number of characters on each of those servers as you have on any live server. So if you have seven on for example Maj'Dul, you can also have 7 on Thurgadin and 7 on Test, the 7 is if you are subbed of course. If your sub lapses, all your characters except the last 2 logged in will be locked unless you buy extra character slots.