I say NO to gluing the bulkhead onto the tank. I don't think that is what you are asking, though. If you have the slip fitting you don't have to use glue on the top portion, but you should glue in the pipe to the fitting on the bottom. If this were to come loose, you would have water everywhere, especially if the return line came loose. Make sure you have a union in the pipe below the bulkhead, and that way you can disconnect things for easy maintenance, etc.
Jack