Is there a plugin for firefox to load urls from a list and save the pages including images to file
I'm not aware of such an add-on, but it might exist. There also might be a Greasemonkey userscript that will load the pages and fire the save.
This thread discusses way to save pages once you have them loaded: How to save a website using firefox. | Firefox Support Forum | Firefox Help.
ScrapBook seems to have a window for that.