No suggestions on your specific questions, but here are a couple of thoughts worth every bit of their cost
Polarizing filters sound like a must for that environment.
If you have a local aquarium to visit, it might make a good practice ground for capturing fish and experimenting with the settings.
Getting or making some sort of flexible hood for your lenses might be worthwhile, to eliminate reflections and glare from the glass under you in the boat. Of course, that would also mean you will be on your hands and knees with you butt up in hte air as you take pictures of the fish, so you may want to make sure the wife *doesn't* have a camera too...
Jim