If you live in EU i suggest you stay on a EU world, everything will be loading abit faster for you.
(And come 3.0, there will be proper EU located servers...or so i've heard.)

The code from the time card im not sure, but i think it might work for all regions.

I live in EU myself, and playing on a Japanese server with alot of friends from all over the world.
But loading speed compared to eu servers differ a tiny abit, and it is noticeable.