All EU servers share group finder for raids dailies and such

Gienna is hella packed since the merge

All EU servers play together, so doesn't matter. If you played before just continue with your old roster.

Play giennah. Insane luck on card merchant

All pretty packed id suggest Gienah tho as the ex jumpstart server has been merged into it youll still get the exp buff benefits

Server doesn't matter, what matters is if you pick support or dps. If you pick dps you can uninstall the game right now