Save to cache: keeps copies of files on your computer for faster browsing.
Don't update: prevents these files to be rewritten/downloaded again for a number of hours, even if the HTTP server tells your browser that it needs to re-download them. Remember that this is just about rewritting the files, and that HandyCache won't delete any file automatically. You need to use the "clean cache" option manually now and then.
I'm planning to create a blog with tutorials in English.