I do a lot of winter waterfowling on the east coast. Not sure how your winter conditions will compare, but I agree with comments above about non-freezing shotguns. If it's much colder than -10C you can even have trouble with oil thickening in a semi and causing trouble. Still, with proper care and maintenance I think you'll do OK with most shotguns - I'd concentrate on fit. I hunt with an Xtrema II and it's a workhorse - stands up well to the salty gritty mud in the Bay of Fundy and cold weather hunts, but you can't overoil it for very cold weather, or it just becomes and expensive single-shot! lol!
Other things that come to mind:
1. Dog? I've hunted waterfowl both with and without a dog. A good dog brings so much to the experience - if you think you can fit a gun dog into your life and take the time to train it etc... I would give it some serious thought. But I would maybe also suggest that you try out waterfowl hunting for a season or two before taking the plunge - it's a big commitment.
2. Keep an eye out for breathable waterproof camo on sale. My most important gear other than my gun and my dog is probably my breathable waders and coat. If you're not warm and dry you won't last long winter waterfowling. Mine is Cabelas First Flight (their cheapest breathables) waders and a Cabelas dry-plus 3-in-one coat. I've got 8 seasons on the coat and those waders last about 3-4 seasons for me because of Fundy mud (gritty - wears them out).
3. Boat? Not sure what your hunting will be like, but especially if you won't have a dog you'll need to think about a boat. It's nice to have a light little canoe for some waters (I have a beat up old sportspal) but also nice to have a jonboat or something like that for bigger water. I went through a few boats before settling on a mod-v 14 foot jonboat wiht a 15 hp. It's the biggest boat that can still be manhandled by two men if the tides strand us or the ramp is not good for my subaru etc... I had smaller boats and did not feel safe with loaded guns in them because they were unstable. You can have lots of fun (and good hunting) if you build a blind onto a stable boat - lots of designs out there or prefab blinds if you got that route.
4. Calls - don't get sucked in by 100$ plus calls as a solution for your first calling attempts. The cheapest calls will make the duckiest sounds in the hands of an experienced caller. It's all about practice - you can waste a lot of money on fancy calls that still won't sound good.
5. Decoys - In my opinion, it has a lot more to do with scouting where the waterfowl are/want to be, and being there with some decoys to bring them into range. You can have all teh decoys in the world, complete with UV paint and flocked heads etc$$$$$$$$$$$$$$$, but if you don't get out before hunting and find out where the birds want to be (and then arrange permission/access etc....) then you'll just be greeting the dawn staring at big investment of fancy decoys. There are also any number of "magic" gimmicks out there in motorized decoys, swimming, spinning, flashing etc... Also very expensive, and SOME are very effective in SOME situations for SOME species, but there is no magic there either - if the ducks don't want to be there you probably won't pull them in with a fancy spinning wing decoy (but you might). I'd start with a dozen and see how it goes.
6. Shooting. Not sure how much wingshooting you do, but practice a lot. If it's not going well, lead more. Then lead more. Then lead so far ahead that you are sure you'll miss infront of the duck and you'll probably kill it. Anyhow - you may be an expert wingshot for all I know, but if not (and probably even if you are) - practice and LEAD! lol!
So, in summary, my opinion for a beginner waterfowler is: gun (nearly any that you shoot well), practice wingshooting, scout, dog (if you're going to stick with it), boat (especially if no dog), "modest" calls and decoys.
Oh, and if you don't have a pre-nup, GET ONE, because waterfowling is HARD of marriages - all gear kicking around the house, getting up at 3 a.m., coming home with muddy gear and dogs, sleeping all afternoon, then doing it again the next weekend... lol!
Have fun.
-Dave
