Does the length of the cable from the computer to the printer matter? I just purchased an Epson 1800 and it is so large I have to relocate it. The cable that came with it is too short. The cable is a USB. Should I move the computer or can I use a longer cable?

If it's more than 5 Meteres you will have to use a USB Hub. Here's a lnk that should answer your query.
http://tinyurl.com/8p84b