Catfish, take a look at the Blue Crab Archives. This forum is part of that. The link is:http://www.blue-crab.org/
It should pretty much tell you everything that you will need to know to catch crabs and answer most, if not all, of your questions. Check with the locals to see what they are using. About the only thing I know about Galveston is that it has a tidal bay off of the Gulf. There must be fishing/crabbing piers in the area.
How about low bridges? Bait shops, tackle stores, all can point you in the right direction. Good luck.