Well i'm not completely sure why you can't wear a hood at a ski resort, but oh well.
Because there's a risk of the hood being caught on the chairlift, which is a legal liability. I know this was an issue for ski hills 5 years ago, but not sure about now (you know.....having lived beside a beach in Australia and all...).
Eastern Mountain Sports, which doesn't carry Mammut, tells if its insulated, and the insulation weight, so you can base the warmth on that.
What type of insulation? Primaloft is probably the best synthetic one found in jackets. Things like thinsulate is also OK. They'll usually tell you how much is in the body, and how much is in the sleeves. Fleece insulation, like they use in Columbia jackets, is also good. Those jackets are good because unlike regular jackets, you can wear just the fleece, or just the shell itself when it's warm-ish, you're exercising, but you still need a jacket to wear.
Every jacket is just a shell with some form of insulation. There are so many ways to do this.
Fleece is great because it keeps you very warm in cold temperatures, it wicks moisture, repels a bit of water, and dries quickly if it does end up wet. The problem is the wind, which goes right through fleece and will cause severe cold from wind. So the shell protects you from cold caused by the wind, while the fleece protects you from the cold caused by the air temperature. Then again, it's great for exercise since it's so breathable (i.e. easy for your perspiration and water vapour to escape), so it's great for exercise.
Buying a jacket to stay warm is actually the easiest demand to satisfy. It only gets tricky when you tell someone that you expect to exercise in it, because then you sweat, which can then freeze and actually make you colder. So warmer jackets for exercise aren't good, while warm-ish, breathable jackets are great. Really great ski jackets are always "thin". I told you you can't have it all.
Again, you can't find a single jacket to handle all that weather, other than perhaps a Columbia zip-out. Their shells aren't very breathable though, nor are they very waterproof. I wouldn't recommend sitting down on a wet bench, or lying down in snow for too long in Columbia ski pants unless they're rated highly (i.e. expensive).
However, if you think of
EVERY jacket as a shell with an insulating layer underneath, and you want flexibility, then perhaps it's best to buy a proper shell, and couple that with a decent fleece underneath. I can do all the things you mentioned when I wear my Arcteryx Gore-Tex shell jacket and a softshell jacket underneath, but it's 2 jackets layered together, not one. It's a bit like a DIY Columbia-style jacket. My softshell jacket provides the warmth of a 200-weight fleece, which is mid-weight. The advantage over a typical fleece is that wind won't go through it when I wear it alone. The best ones are lined with Gore Windstopper. The disadvantage is that they're always a bit more expensive, and around 20% less breathable than a regular fleece without the Windstopper lining.
So for me: Hardshell Gore-tex Shell jacket + windproof softshell jacket + very thin fleece shirt underneath.
I think in America, you can get the softshell and Goretex shell for $350 or so if you look hard enough, and aren't too picky with the brand.