Using CacheSet, how do you best go about determining the appropriate and optimal minimum/maximum settings?
A matter of trial and error. Listen to and watch your computer. One of the signs you need a larger System (File) Cache is e.g. that opening a folder takes more time than usual and when you hear/see the harddrive working. Because then Windows needs to find the location of all the separate files again and extract all the icons from those files again as well.