A. If you are not sure what size ski jacket you need it is worth trying on a couple of jackets as individual brands will fit differently. Some brands may come up smaller than others even if they are the same size as styles can vary.
Your jacket should be relatively fitted with enough room in the arms and shoulders so you don’t feel restricted. Too big and cold air will be able to get in through the bottom and sleeves.
If it is an insulated ski jacket you won’t need to allow as much room for layers as this jacket should be warm enough. If it is a thinner shell jacket then you should allow a bit more room for extra layers to keep you warm. It is worth trying on any layers you plan on wearing with your new ski jacket before you go.
Women’s ski jackets will tend to be more fitted and wider around the hips whilst men’s ski jackets will be wider on the shoulders and narrower on the hips. It is usually best to stick to your own gender in jackets unless you have particularly broad shoulders.