I was wondering if I can use a tier 7 battleship for the clan (TAW).
You can use what ever ship you would like to use! T7 is a great tier for the Soviet Battleships.
Looks like you have your application filled out and are awaiting a bootcamp. They'll get you taken care of. I am sure once you get thru onbaording you can apply for the in game clan and get hooked up to start rocking the [TAW] next to your name and enjoy the vast in game discounts and bonuses the clan has to offer thru years of massing resources. Hope to see you in the fleet soon so we can play together.