I take it you are planning on doing lift accessed backcountry. You are probably looking for a pack that carries around 20 maybe 25 liters. Skins take up a fair amount of room. A Dakin Heli pack will probably do that for you though you won't be able to carry much in the way of extras. If you are planning on doing any sort of touring I would highly recommend going up to a 30-35 liter pack. Cinch it down if you don't need the space. I would definitely plan on carrying some water and food with you.
Pieps DSP tour is a solid beacon. No worries there. Learn how to use it as much as you can before your level I.
I would say get a 300cm probe. I use a 340. Overkill in Colorado, but when I am in the PNW it is pretty obvious that you want one for the deeper maritime snow pack, which Whistler has.
As far as shovels go, get one with a metal blade. Several good companies for this. I like shovels that can convert into a snow hoe. That can be very handy for moving snow quickly without picking it up. In a team rescue situation this can be useful.