WOW, where to start.
Shops don't normally produce their own products, let alone something as technical as outerwear.
No shop will sustain any sort of business only selling outerwear. You should probably carry all things skiing.
So do you want to have a shop or an outerwear line?
You are never going to get contact info for a manufacturer through NS. Start poking around the industry and see where everyone else gets their stuff made, for how much, and the other 1283729138098 details. This should take months to years to develop a solid plan/business model.
My best advice, is to start drawing. Once you have a BOOK of good designs and a solid understanding of how they might actually fit, buy a sewing machine and some material. You will find out quickly how much you do or don't like working with textiles. I taught myself to sew quite easily, but trust me you will be doing it for WEEKS before you have anything you are proud of, especially outerwear.
Honestly, you may think you are talking about a small little business, but you are quite literally talking about a HUGEEEEEEEE project.