Huan: After a few hundred shots, I know better than the camera!
Different fish need different exposure speeds, say a placid fish can be shot at 1/80, but a fast moving wrasse need 1/200 in order to get a decent pic. Same with the aperture, I decide what depth of field I want. These days I set the exposure and aperture without really thinking, all it takes is a quick glance around to gauge the amount of natural light available, and what "prey" I'm after.
Miyagi: I use a Olympus 5050z. I am out of the loop on current cameras, but the old adage of "buy the best you can afford", always holds. Canon, Sony and Olympus all make good point-and-shoot cameras with polycarbonate housings. You should be able to get a decent setup for 1k-2k US.
MKDVR: Yes, the more central the flash position, the more likely that light from the flash will be directed back into the lens. Shift the flash to one side and you get a rapid reduction in backscatter as the reflected light probability follows a Sine curve. Kinda hard to explain without a pic.
I'm off to see my family for easter, back in a week. I'll post a few more pic then.
