Not really been following this till now- can I assume whether someone is suitable or wants to be either a lead or a follower is tied to if they are a dominante or submissive kind of person?
Based on my own somewhat limited experience, but also from the statements of some of my friends who dance competitively, it's not quite that simple. At a certain level both partners will know how to dance either role. In traditional m-f pairings, it is expected that the man leads, but at a competition the two will subtly pass it back and forth in order to preserve energy. Leading is physically more taxing, and while a good pairing is way more efficient, it can still make sense to share the load a bit. Has to be done carefully though, as judges may strike off marks if it is obvious that the woman is leading. Generally also fun to pass back and forth if one of the two is significantly better -- had that with a friend of mine, where I was leading in our f-f pairing, but when we were getting boxed in, she just said "hold on for a moment", and we were suddenly on the other half of the dancefloor.
TL/DR: not that simple. You can have dominant followers etc.