I think there are many ways to tackle snow shoots. You can choose to shoot close and wide for dramatic perspective, especially for jumps and tricks, or long for faster, more direct downhill stuff. Whether you need a flash depends on where you choose to shoot, how far from your subject you are, how powerful your flash is and how bright the ambient light. If your subjects are backlit or top lit then a flash might be a big help, but you'll need to be fairly close for it to have any effect. If they are front lit then a flash won't do anything useful for you. A CPL will give you the option of darkening the sky and may bring out more punch in coloured outfits, if the sun is striking the scene roughly perpendicular to the lens axis. If the sun is behind you or in front of you a CPL will have little useful effect.
Regarding WB, if you shoot raw it won't matter much, if at all, but I find a daylight setting gets me into the right ballpark. As for exposure, I'd be shooting with manual exposure and practising ETTR to the full by spot metering off the brightest (important) part of the scene and placing those highlight tones at the right hand edge of the histogram. For a Canon shooter that threshold is at +3. For Nikon, which I do not shoot, I think around +2 1/3 is about right, but check your histogram and look for a hint of blinkies to indicate that you are where you want to be exposure wise. Here's a typical example of one of my snowy exposures. The histogram and blinkies are perfect (IMHO)....
In bright sunshine a good starting point for a manual exposure without flash would be 1/1600, f/5.6, 200 ISO, but you'll need to tailor to the exact conditions (angle of sun, how it reflects off the snow and back onto your subject) and your own camera's exact performance. If you use flash then you will have a problem with sync speed. I'm assuming that yours is 1/200, but I don't know for sure. The only way to get down from 1/1600 to 1/200 is to decrease aperture from f/5.6 to f/16, or if you can get a genuine 100 ISO from your camera then f/11 should be about right. The problem with that is that your flash will become pretty ineffective with the lens stopped down that far. If you can find a shadier spot, or have a bit of haze/cloud cover you might have an easier time of it.
You might try a Google image search and just find some snow pictures you like and see whether there is EXIF included. Then you can see what sort of focal lengths and other settings were used.
Good luck. Have fun. Be safe.
EDIT : Actually, here is a (long) shot of mine showing how the resident pro was shooting people as they crested a jump. Being so close, but wide angle, he would have got a much more drmatic shot than I was able to....
You might also observe that both images have identical exposure settings. This is because I locked my exposure manually once I had it dialed in correctly and confirmed by checking the histogram and looking for blinkies. In fact I shot around 140 images over a 40 minute period using those settings and every one turned out equally well. The light hadn't changed so there was no reason for the exposures to. Autoexposure, whether with or without EC, would have been all over the place as I grabbed differing amounts of snow vs sky and had different tones of skiwear in the middle of the scene. There's a time and a place for autoexposure, but in conditions of very consistent lighting I think manual is the better option.
if I can get the settings pretty much perfect then I can just leave it set up for her to point and click stuff. 
