The GL-2 has a neutral density filter built in. This will get you to the exposure you need for brighter scenes. You can go to shutter priority and set the speed higher also. I have never overloaded the imager in the snow. White balance in auto is very good. If you are shooting under varying conditions, leave it in auto- you can always tweak it later. If you shoot in the shade, early morning, evening, or cloudy conditions, you can set the white balance with a white card.
Keith Breazeal/Flight Video Magazine
http://www.kbvp.com