I have been successful in teaching a rooster to not attack me.  But I was not able to teach that rooster to not attack my wife or any other human being.  I would get rid of the aggressive one.  Why put others at risk if you don't have to even if you can train him to not attack you?  I do believe a tendency toward aggressiveness can be hereditary.  Another argument to not allow him to breed.
What you described with the first rooster's behavior is simply dominant rooster behavior.  Finding food for them, taking care of the flock, and all that.  If the non-dominant roosters tried that, he would see that as a threat to his dominance and beat them up.  You have no idea how the others will behave when they are dominant until they are dominant.  
I pretty much agree with Janinepeters on the red one and breeding a chicken with temperament/personality issues.  
I have single combed chickens and it occasionally, but not often, gets below zero Fahrenheit here.  I don't have frostbite issues in an uninsulated, unheated, large, well-ventilated coop.  But a single comb does put them more at risk for frostbite.  While it is not an overriding concern for me, it is something to consider.  If everything else were equal, it could sway my decision.
You will do whatever you will do.  But this is my opinion.  Good luck!