Glad to see that you've ordered Martin Edge's book. There is an immense amount of info in there for both the beginner and intermediate photog. Again, I strongly recommend installing a vacuum system to verify that everything is watertight. I prefer the Leak Sentinel from Vivid Housing as it provides a constant visual indication that the vacuum is intact. Others prefer a purely mechanical system. Personal preference I guess.
One final piece of advice. If you're rushed to get your kit together, then don't take it down. This happens most frequently on a liveaboard where you're changing chips or batteries after dives. That's why I use a vacuum system to verify that everything is together.
Plus NEVER, NEVER allow your kit to set in the rinse tank unattended. When you finish a dive, hand it up to the crew and instruct them to put it on the deck or on the camera table, somewhere out of the way. Never allow them to put it into the rinse tank. When you get on deck, then rinse your kit yourself and put it on the camera table. Don't leave it in the rinse tank. Rinse tank collisions with other rigs are a major cause of floods.
Never jump in or back roll holding your rig. This might work for small P&S, but not for larger SLR rigs. The impact with the water can dislodge ports, etc.
Finally, try to find a photo instructor to help you get started. One who is willing to spend time teaching you the basics of caring for your rig and taking photos. The Edge book will help a lot.
BTW Martin Edge is based in the UK, near London I believe. Once you get a little experience, a session with him would be great. He has a web site somewhere.