If you haven't already, invest in the close up kit and the external strobe. When using the camera with the Marine lens that should have come with your camera, you will get very good shots in the 4-6 foot range. However, the internal strobe is going to give you a little back scatter even though there is a diffuser. So, use the external strobe to get rid of back scatter. Also, the close up/macro kit will allow you to get perfect shots every time.
There is a trick to keeping your housing from flooding, though. Inspect the seal ever time you close it. Since the housing opens fully, that is pretty simple. Plus, since they use a silicone seal, you don't need to grease it. When you put the back on, use their little rubber latch keeper. While at depth, the housing will be held tightly closed by water pressure, it is possible to pop a latch open while climbing into the boat. The funky rubber strap is a great insurance policy.
Take lots of pictures and show them to as many people as you can.
Just my $.02
RayC