If you made something from a printed or online pattern, you can assume it is copyrighted. I know your friends mean well, but in reality, nobody wants to buy something made from a pattern or kit. Design your own. Your designs are copyrighted if you simply declare it so, but there's not much you can do, as an individual, if someone copies it. Just be ready with the next cutting-edge design. If you're a good designer, you may just want to sell the patterns. Often with crafting, the fun is in making the item, not owning it.
The only license you need is a state tax number. This can get you discounts on yarn and supplies, or at the very least make it so you don't have to pay sales tax on what you buy.
Go sole proprietor unless your product would have liability issues that could result in someone trying to sue you.
I have found that decorative items don't do well online. If it's also useful, you will have better luck.
I started on Ebay with my sewing stuff. It's great for testing new items to see what will sell, and to learn how to pack and ship. But I have used my own website for several years now.
I have my taxes done at H&R block. I just don't fool around with that stuff. They gave me a notebook with everything that I am supposed to keep track of, like electricity and even the mortgage, and then the tax guy figures out what the percentage is that you can claim on each thing.
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