Power window fuses aren't in the main fuse box, they are in a separate box (or boxes) somewhere on the firewall.
As for the brake lights, did you verify that the brake light bulbs (single filament) aren't burned out? Did you also check the function of the brake light switch? The older brake light switches do have a tendency to stick. On the 4.5 the switch would stick, then slowly engage giving very delayed brake lights. replacing the switch cured that problem.
Fuel gauge could be dead, or the sender dead or the electrical lead to the gauge disconnected, or, or, or....
While you are looking at the fuses, just go ahead and replace everyone in the main box. They may look good, yet in fact be bad. Change them all, it isn't an expensive proposition.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.