My first suggestion would be to seriously consider going with a digital set-up. For about the same price as the MMIIex, you can get a very nice digital rig. But if you'v already made that decision.....
The first thing to buy is Joe Liburdi's book The Complete Guide to Sea & Sea available at Amazon.com. It will explain how the camera and accessories works as well as basic explanation of composition. Another good book for all photographers to have is Jim Church's book on composition.
When I had my MMIIex, my two favorite lenses were the 16mm wide angle for scenic and close up wide angle shots and the 2T macro for the really close ones. There's also a 20mm wide angle and a 3T macro. You'll need the Optic High Point Viewfinder. There are masks inside that let you frame the three lenses properly since the viewfinder is pretty much useless.
If you're going to use add-on lenses, I high recommend adding a lens caddy to safely carry your lenses on your dives and not have to put them in a pocket. And if you plan to change lenses underwater, you'll want the security of a
Save-A-Lens Kit. It's hard to see in the photo but it's an unobtrusive cable system that keeps your lenses tethered to your camera in case you should drop one. After losing a lens in the deep blue...I won't change lenses in the water without one!
As for strobes, Sea and Sea YS90DX is my choice. I've always used and liked S&S strobes and the YS90DX will serve double duty if you ever do switch to digital.
