I would echo the view that keeping it simple is the way ahead.
Taking pictures underwater is a skill that requires a fair bit of concentration at first, and it's not a good idea to introduce it while you're still thinking about your diving.
Think about getting a few dives in on the trip before you take the camera, and take a peak performance bouyancy course if you can; either that or get an experienced buddy to help you develop your bouyancy skills until hovering without kicking or sculling is second-nature.
Your bouyancy needs to be instructor standard, or preferably better, to be an effective and safe underwater photographer. The starting point is getting your weighting right - most novices dive with too much weight, and good bouyancy control is then impossible. Look at how much lead your dive guide uses, it will be less than you'd expect. Do a weight check as you've been trained to - as you exhale you should be *just* sinking very slowly, not dropping like a stone when you dump air. If you are constantly adjusting the amount of air in your BCD during the dive, you're probably over-weighted. I probably touch mine two or three times during a 60-90 minute dive.
It's very easy indeed to damage reefs with fintips and hands when you're taking pictures, as you tend to forget about where your limbs are when you're looking through the viewfinder. Most of us have seen divers with point and shoot cameras kicking coral, or grabbing it to steady themselves, and they don't give us a good name.
The bottom line is learn to enjoy your diving first, and get good at it, before you start with the camera!
As for looking after your kit, rinse the camera after every dive. Ideally soak it in a rinse tank of fresh water, but don't let it bang against other cameras or computers.
I always take my own bucket (well, crate actually, I use an SLRand two strobes) so that I have my own rinse tank. You can use the litte shower things they have on some dive boats, but be careful not to force water into the seals and buttons.
At the end of the day soak for 30 mins in fresh water, and work all the controls to dislodge salt water. Then leave to dry and open it if you need to to download your great pictures and recharge the batteries. Always open a housing upside down so any drops of water drip away, not onto your gear. Take cotton buds with you so you can clean O ring grooves throughly, and make sure you have no dust, sand or hair on your O ring or in the groove before you put it back together. O rings need to be lightly greased before you put them back in.
Finally, others have mentioned the "Magic Filter", which is an easy way of getting nice looking pictures without using a strobe.
Have fun!