My new Canon T2i UW setup

[runNEOrun]

Here is my Canon T2i within an Ikelite underwater housing and 8" dome. I have two lenses to pick from -- Tokina 10-17mm FE lens and the kit Canon 18-55mm lens. Attached are Ikelite DS-51 substrobe using Ultralight arm and lastly GoPro HD Hero2 mounted on top. Eventually, I want to get a Light & Motion Sola 1200 Video to be my flood and focus light.

Question, what are typical settings I should be using for either still or video taking? I typically take many of my photos in 'P' mode but want/need to get into using manual mode.

Thanks for your time!