Good luck in your merch business. I've been a member since the first month. It really is a set it and forget it business. Create a design (I use Gimp) upload and you are done. Create a dog that won't sell? No worries. Amazon will take it down if it doesn't sell within 90 days. Create, upload, repeat. Let them worry about the rest.
RE: Yeah..I got into Merch by Amazon for my T-Shirt Designs