[KenByrne]

I'm curious why you can't change the settings in the housing. The housing description states that all functions are available.

For wide shots I'd turn off the internal flash and try program mode or set Tv mode and set the shutter speed to 1/60 with ISO 80 or 100.

For macro shots I'd keep use the flash I'd also keep the lens at the wide setting so I got close rather than zooming in from a distance as this technique will give better colour saturation. I'd be aiming to use something around f8 f11 or f16. On a camera like the G9 the aperture isn't so critical as the sensor size means that you get a good depth of field at all apertures but it does effect the background exposure.

These are just starting points play around with the settings when you've tried it out and seen the results.