The method of how to adjust the rear brake is in the FSM if your unsure. There quite easy though, you want as little resistance as possible on the brake shoes but as little travel as possible at the lever, you just find that mid ground point between brake shoes rubbing and then back it off a half turn at a time until your happy.
Edit: The vent line runs up the frame to the front of the tank just behind the steering stem.
Edit: The vent line runs up the frame to the front of the tank just behind the steering stem.