I would recommend the Seagate GoFlex drives - you can get up to 1.5TB in a bus-powered drive, no power cords, etc. You can also buy a new little plugin for the back (maybe $30?) that will convert it to a thunderbolt drive. I use my 1TB version to drag around all of my movies on really long trips.
Also, you do have left & right clicks on your trackpad -- just click on the right-half of the trackpad and you should get the context menus / normal right-click type of behaviour.
I'm seriously considering getting MacDive and just doing everything by hand. Or reverse engineer the Galileo data stream over iRDA so I can still download. Or just buy a couple of new dive computers that it DOES support.