Hello and welcome
I think you have 2 basic choices for your camera
the canon WP-DC35 40m housing or the Ikelite 60m housing.
I think the Ikelite is more expensive, but has more options. I think the basic canon one should be ok for day to day, but if you want something a bit better that has a bit more expansion options and you don't mind the extra $ I'd go for the Ikelite.
I'm still learning under water photography, but here is what I have learnt so far..
perfect your buoyancy with the camera. Mostly practice, but you can do you Peak Performance Buoyancy spec to help a little.
Get as close as you can to your subject (and then a little closer). The less water between the lens and the subject the better it will come out.
Try to be lower than your subject in the water so that you are shooting up for better composition.
Reset you white balance every few meters (you may want to get some white/ grey slates for this, some people use their hand successfully).
Best pictures without strobes are in 10m and less. That is not to say you won't still get some good pics down at 20m plus, but you will more likely have the colours washed out. You can get red filters to help restores the reds that go at depth (I've personally not tried these yet). Remember strobes have an effective range and you will need to get within a couple of meters.
I've seen some good pics taken with fish eye lenses, they let in a bit more light in and work really well under water. It is something on my shopping list.
Personally I think you'd be best getting use to the camera underwater without the extras (strobes and lenses), then add them on as you feel ready. Get some pool time if you can.
Here is a link with some of my pics (I'm still working on improving). These were with a Fuji EXR200 P&S with no stobes or additional lenses.
http://www.thescubasite.com/Scuba-Forum/Scuba-Diving-Stories/1762-Egypt-Trip
The last pic of the moray shows the wash out you get at the deeper depths (I wasn't gonna get that close to that monster either lol)