Affiliate Marketing Secrets

Do ethnic Korean-Japanese (Korean heritage born in Japan) people tend to keep Korean last (family) names, or adopt Japanese ones?
What about first (given) names?
Does this differ depending on whether the Korean-Japanese is affiliated with North Korea or South Korea?
What percentage of Korean-Japanese go to special Korean schools in Japan?
Do those Korean school students all have Korean-style dress uniform for the female students? Or is that just North Korean schools in Japan?