I shoot film, both 35mm and Medium Format, and develop my black and white film myself, so I'm right there with you on using film.
But I agree that the learning curve for film is so much longer than it is for digital. You will progress much faster using digital than film.
If you are still interested in using film, I recommend you pick up a Nikonos V and the legendary 15mm lens for wide angle work. The Nikonos V costs less than $300 these days. Velvia 50 was what virtually all the uw photographers used to shoot and the very saturated chromes looked fabulous showing the colors of the reef.
The Martin Edge book is a "must have" if you're an uw photographer. Lots of great information in there. I refer to the book again and again.
Shooting uw is completely different from shooting on land (as we like to call it, shooting "topside"). Most of the time, the strobes used are ones that are dedicated for uw use. However, they do make housings for some topside strobes. I haven't used my SB 800 underwater, but I've heard that using topside strobes, although there are a few advantages, basically is not as good compared to using dedicated uw strobes such as the ones made by Ikelite, Sea & Sea and Inon.
Another good resource is Reef Photo and Video, one of the sponsors of wetpixel. They are friendly and helpful and can often help you make descisions about the right gear to purchase, given your situation and the equipment you are using.
Lastly, feel free to come back here again and again with your questions. We're all willing to help!
Ellen