I cannot explain what the difference is between his role with SCV and his role with the Troopers, as that remains to be seen. But I do know that yes, he does do some touring with SCV during the summer.
Gail loved the Vanguard. It was his world and meant the world to him. Unless you've marched in the Vanguard, you cannot feel this feeling. Unless, of course, you were its founder, which Gail was.