The one on the left turns on the front fog lights. If you have I believe a '96-'99.5 they are integrated into the headlight housing and are called "city/driving" lights. If you have anything after that, they are in the lower bumper valence. The one on the right controls the rear fog light in the left tail light housing. I couldn't tell you if you still have it because of your situation. The left triangular light is green, and the other orange, right?

 

Yes green and orange. Right one orange lights up when hit brakes

 

Yeah, this is where my knowledge stops. Sorry.

 

Is 20w 100ohm too small

 

I wouldn't think so. Worth a try.

 

Does it matter where resistors go. Go on led light wire or car wire harness

 

Put 10w 100ohm resistor in. Dash light still on in cluster. Goes off when hit brake? Risistor too small.

 

For the tail lights we usually use 25w 50ohm resistor for anything related to the tail lights.
On the B5 you will NEVER get error message for plate bulbs as well as backup bulbs when you change them to LED.