New
#21
Yes date modified and size are the only filters that show in general folders when clicking in the search box. If you were My Pictures or My Music you would see different filters.
But if you know the filter then you can just type it. A ":" is required after any filter. So typing filename: or ext: in explorer you should see it turn blue then you type the filename or extension you wish to search for.
No changes to the index options are required to use the filters. More filters and examples can be found here.
EDIT: Did you try typing kind:
and get a list of types?