Advising on Digital Photo Printing Project

Hi Freelancers- I have a company that sells artwork by a couple artists. I want to start selling digitally-printed reproductions of their art. Some are photographers, some make drawings, etc. I have a high-res scanner, and so do my artists. I need to communicate to them what the file submission requirements are for my website. I have researched this already online, but I need someone who knows what they are talking about to explain it to me simply. $40 for your time and a page of compiled answers to these questions: 1. Sizes offered are: 4x6, 8x10, 10x10, 11x14, 16x20, 20x20, 24x36 2. I use this website for my prints: [login to view URL] 3. They use Kodak Endura Matte/Luster paper. 4. I need to tell artists what the minimum file requirements are and what the maximum are for each size and in general. I also need to tell them what size their thumbnails need to be to load on my small wordpress site and still have enough quality to be seen/zoomed in on. 5. Another reason I need help with this is because I know that some images can be lower in size or pixel count if they are, for example, black and white drawing vs. full color photograph. Please articulate to me, as if I am one of these artists, how this works. 6. Please type a one-sheet for this that I can use when talking to my artists about file requirements.