According to lore could a hero of different race be accepted as stronghold chief because of his glorios deeds or by overthrowing the old leader?

If not, would a tribe accept a leader that was massively helped by an outsider to achieve power?

I wouldn't be that surprised if this happened.

Nor would I. While it may of been rare due to most peoples distaste for the Orcs way back when, I'd think they themselves would be more accepting of the idea.

I would say that would be rather extraordinary