Hmmm ... I guess it depends on whether you want it to stand out a lot or not.
With a white car, I might consider making the calipers a very glossy white - if you want to make a definitive statement! To be more subdued, a glossy black or silver might look good too.
In terms of the type of paint, I don't know the answer to that. Clearly, you would need something capable of withstanding high heat!
Z