I prefer putting brushes in my C: > Documents and Settings > (username) > .gimp-2.2 > brushes folder, but that's a preference At least that will work without admin rights, but will only add the brushes for your user and not everyone that uses the computer

For normal truetype fonts, I'd put them in the Windows Fonts folder instead in the Control Panel so all programs can use them For anything else, yeah, you can use similar steps as for brushes, but using the appropriate folder instead of the brushes one inside the gimp folder