Hella Optilux Fogs Those are the fogs I have, they are very bright and look 100 times better than the ugly stock plastic lenses.
Those Optilux 2500's take an H3 bulb. So you would want an HID kit with an h3 bulb in whatever color you want, 6k, 8k, 10k whatever.
I've never used a bi xenon kit. At the time I had stock capsules I only did city driving so I never used hi beams. Now that I have my projectors they only take single beams.
If you use your hi beams, then I would suggest getting the dual beam kit.