The Bosch sign in the window or on the wall will lead customers to think they are dealing with a Bosch sponsored outlet BCS or Ecp Bosch in the customers eyes good or bad you will all be the same they wont supply a Bosch sign saying better dealer.
as for joining i suspect the only qualification you will need is MONEY and BCS members can look forward to competing with Bosch outlets that discount Bosch parts !

regards chris