In terms of shooting in the park, approach it like you would a skateboarding shoot. Park skiing isnt all that much different than skateboarding.
When trying to get powder shots, try to shoot on the bluebird day after a storm. The lighting on bluebird days is good, and you still have at least a little untracked snow.
If you do shoot in a storm, don't be afraid to turn up your iso to get a fast shutter speed. It's better to have a little noise than a blurry picture.