I have both a male and a female dominant (yes, I'm greedy), and there isn't a big difference between the two based on gender. There are some small differences (for instance, I think you're generally more likely to receive oral sex from a dominant woman than a dominant man), but it really comes down to their individual personalities and preferences.

To answer your other question, I am a female submissive, and I'm right in the middle of the Kinsey scale -- I have very little preference between men and women, although I think I might be getting to prefer women somewhat. Also, I am occasionally attracted to submissive women but never to submissive men.