Yes, sounds like iMovie will work out well for you. The only tips I can think of is to choose your music based on how you want to set your mood, and don't think you *have* to use Nickelback for snowboarding. It's over done.
I wouldn't use the photo camera for video, you'll be disappointed at how crappy it looks compared to the video camera. Don't worry about getting a "good" video camera.
Editing, I can't give much advice for... make sure your video tells a story. What do you want your video to be 'saying'... "we had a lot of fun snowboarding" or "we're the badasses of snow boarding" or "we are the comedy caravan of snowboarding" or whatever.
Have a plan before you go out there... what are all the things you want to get on camera, what "atmospheric" stuff do you want people to see, etc.
Keep your use of zooming the lense to an absolute minimum.
I'm a hobbiest too, but I recall someone once telling me that you will throw away 75% of everything you shoot... that is... if you shoot 4 hours of footage, you're only likely going to get 1 hour of good material.
If your camera has a motion correction mode, I'd turn that on if you think you're going to film *and* snowboard. The latest iMovie has a motion correction algorithm built in, so that will help you.
Hope this helps!