Eastern European = highly technical British = being British level American = hit and don't get hit (cowardly runner style) Mexican = pressure + war
Pretty hard to gauge. The only fighter I know from there is Ippo Makunouchi who had a great dempsey roll.
There isn't one; there's never been one. Koichi Wajima was about as weird as it got in terms of style. There are some dominant gyms that teach aggressive boxing after drilling techniques, but there are gyms like that in every country.
Cowardly runner style? Sugar Ray Leonard, a brilliant boxer/puncher, would f*ck your hero Pac up something ugly. Apparently you've never seen a Marvin Hagler fight, either.