Well, our car is a 24 hour endurance race car, so we have hacked the wiring a little, but those temp sensors should be the same on our car (1989 engine I think) 325is.
I am working in Indonesia, so not able to look at the car and cant remember from memory what our temp sensors look like....I do think we have a blue and brown though!
In terms of plugs, use the nice cheap copper core $2 a plug things from Pelican or similar. We change the plugs every other race as a precaution (we do about 800-1000 miles in a race). We have tried the more expensive Bosch irridium things and there was no differance, in fact we even felt it was missing a little nearer the red line, so we changed back.
