Online Apparel Designer

Looking to have an apparel website built like customink.com. I want to be able to integrate a small catalog of items and have users be able to upload their own artwork, preload any and all logos on the backend to be utilized in the designer in order for clients to choose from, have text insert capabilities etc. I would like the site to be built thru Shopify and once ordered, the artwork is sent to my backend in a print ready format with an order form of the products. Designer also needs to have a setting to make sure only good artwork is used and warns the client of poor quality art before placing the order. I'm ok with using a plugin that works and building something around it. Site also needs to be SEO built in and some backlinks.