Consider installing a vacuum system to double check the integrity of your kit before you get it wet. I installed one from Vivid Housings and am quite satisfied with it.
Also consider adding your camera, lenses and UW equipment to an insurance policy that covers "all risk". Generally you can get one as an addendum to your homeowners policy. If you're eligible for USAA, they have an excellent Valuable Personal Property policy that provides this coverage.
Get a copy of The Underwater Photographer by Martin Edge. I believe that the 4th edition is the latest. Many UW photogs consider this to be the bible.
Look at Underwater Photo Guide and Dive Photo Guide web sites. Loads of info there.
Consider adding a Nikkor 60 mm AF-S lens for close-up. You may need to get another port for it. I'm not familiar with Ikelite housing and ports.
When you use your kit in the pool, make sure that you soak and rinse everything thoroughly. Chlorine is very rough on seal, etc.