No it is not enough to go around. Leghorns are also very dominant in a flock so the new roo would suffer. I would not rehome the little one until I heard it crow.
Yup Susan is a Sam for certain. Looks to me to be a leghorn male.
It is amazing how much the little ones eat. Yes keep food available 24/7 they eat a lot because it is needed. They are going to be growing in leaps and bounds. Fresh food and water all the time is very important. If they are...