Do certain races have higher incidence of syphilis?

No- it's complicated. To associate a specific race with the incidence of syphilis, provides only a superficial and misleading impression. It's important to know that people in lower socio-economic groups have high incidences- these groups have a greater number of people of a specific ethnicity. Granted, it has been referred in the past to as the "english" disease, the "french" disease, or the "italian"disease, .
Yes. Infection frequency appears to relate to availability of health care and willingness to seek it. However, all soceo-economic groups and races are affected.
Wrong question. "race" is a political concept, not a scientific one. Discussions comparing "races" serve no purpose and do much harm. Within particular communities, different "races" may have different rates of lifestyle-related diseases due to social factors. One's genetic heritage may put a person at more or less risk for some diseases (genetic, immune-related), but syphilis is not one of them.