Welcome to UW Photography!! You're going to love it - even when it frustrates you to the point of wanting to toss your rig overboard!
Here's some getting started tips that apply to a great range of compact digitals, so don't worry about the model number:
http://www.scubaboard.com/showpost.php?p=1103341&postcount=4
Here is a link on how to get the most of your manual white balance setting. With this setting you do not need the filter. I personally don't much care for the filter in a lot of cases, though for some shots it does a really nice job.
http://www.scubaboard.com/showthread.php?p=862362&posted=1#post862362
Have a look around the forum here for recent threads, too. There are lots of us here asking questions and providing information so you are bound to glean some useful tidbits.
If you can't find the answers to your questions, ask away!
As for the oring, this is all that stands between you and a messy, wet paperweight, so ample care and attention should be paid.
- tiny amount of the correct grease (probably some came with the housing) when it needs it. It should be a little shiny, not ever globby.
- examine the oring for dirt, dust, sand, hair and nicks/cuts every time you open the housing.
- carefully seal your housing and re-inspect for o-ring pooching out or extra dirt
- I do not remove my oring unless it needs it. The more you stretch it, the shorter its lifespan.
- don't stretch the oring! Gently rub it between your fingers to apply grease and/or to remove debris
- check your seal before hitting the water and again at the surface
- bring a spare
- clean the grooves of the housing with those sponge tipped makeup applicators - they are cheap, easy to find and don't leave lint
Learn your camera in the housing on land before your trip!
Have fun and shoot lots
