if i was to get this housing, aside from extra o-rings, what other accessories do i need to get?
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
Having an extra tube of o-ring grease is nice. I'd order that along with an extra o-ring. That should have you set up for at least a couple of years of UW camera use.
At some point, you might want to buy a used G11 on Ebay for a backup.
Getting 3 o-rings is definitely overkill. These canon housings are built well and the o-rings last a very long time. I've had 3 canon housings and never had to change an o-ring on one in 3 yrs. Once you take it out occasionally and give it a little grease, it should last you for years. You definitely need to get the silicon and you can never have too much. Another thing you may consider buying would be the weights, especially if you don't have a strobe to weigh your rig down a bit. The housing will be positively buoyant and will take any chance to float on up which can be a real pain in the neck . Good luck.
Same had mine for 2 years never changed
i found silcone pump very handy for those stuck buttons also
have a look here for maintenance on G series houseings (and most others)
Underwater Camera Maintenance
thanks for the link, i saw that in one of my searches, i even saw one where you use a sanitary napkin to avoid the splashing inside the housing if every it gets flooded