Unfortunately, you are using an out of date browser which is not fully compatible. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
Backing up everything takes up so much room but I'm not sure which files are the important ones. More specifically, where are the customer work orders located so that I can back up those?
I'm not a fullcalc user, but wonder how you are backing up that is taking a long time? It would seem best to back up all of the files, if possible. (even the whole folder)
A series of flash drives should back it up in seconds. (one for each day of the week) FC isnt storing images or anything like that, so its space requirements should be minimal.