Black R

I want to learn as much as possible about the Silvia s15 headlights.

I've seen black vs silver housings and hid vs non-hid.

How do the lights work in oem form?

If I bought non-hid lights, could I use an aftermarket hid kit or would the light pattern suck?

What do each of the bulbs do?
Is there integrated driving lights or parking lights?
Oem fogs in there somewhere?

If you have some links, please share.

Thanks.