A Community Leader might be better to provide and answer, but yes, the forum has a maximum size for image uploads. In fact each file type has different limitations. JPG images can be 4000 pixels wide to a maximum of 4.5 MB (I'm not exactly sure, but that's a close guess). My recommendation is set to 96 ppi for any uploads larger than 8 inches wide. A good resolution for printing is not the same as a good resolution for viewing online. 96 ppi looks fine online, though is poor for a print.

Maps I intend to print is never less than 300 ppi. Of course, I run Gamer Printshop, and have access to large format and high resolution scanners, large format B/W copier/printer, 12" x 18" color laser printer, and 1440 ppi large format inkjet printer up to 44" wide. I also have large format laminators, cutters and other equipment to make map-making a breeze. So using Kinko's would be a downgrade from what I can do now.