bulb recommendations for W201 euros

For those with euros for their W201s, what bulb combo (main/fog) is the best? I want something that is affordable yet of good quality and brightness. For the fog, I am looking for a pair with a blueish color because I kind of like the reflection of blue off the fog reflectors.

In the main light unit, there is the socket for the main bulb. But next to it, there is this round black piece that looks like a socket or plug for something. What is that for? Thanks.