I probably don't have EXIF extraction turned on that site; although you can see an example page at:
and, correct, the filename, etc is NOT taken from exif information automatically (I didnt realize you were asking that). Since all cameras have their own formats, its my experience that you frequently have different field names for same items (i.e. no standards). As I said, EXIF/IPTC is not searched, but it could be.
I also misunderstood the selectable categories question - yes, you can have unlimited subcategories, but no, you can only select 2 additional cateogries. If you have 5, then you'd have to modify the code to accomidate you.