Three is no real proof to that. Unless I don't know something.
But many breeders feed live, and many feed frozen. It's just preference. I do both, depending on size requirements and such.
Unless this snake is over 4-5 years old and has been feeding frozen their entire lives, he should be a good eater. You could give him live, and he will know what to do. I worry more about my corn snake, because being 5+ years old, she hardly constricts the frozen that I give her.
Females do get bigger than males in ball pythons. It's not as significant for balls, but it's true for boas as well which it can be a 2-3ft difference.
For corn snakes, males get bigger than females.
Just remember, to keep your two snakes in different enclosures! :]
In the frozen vs live thing.. if your picking up mice at the store, thats a very very large expense per week. Especially with 2+ snakes.. it can quickly sum up to over 20 dollars a month. I breed and buy frozen online, which is much cheaper and less of a hassle. I currently have to buy 2 live mice from the pet store a week and it's a pain in my rear. Because of this, I badly want to get my first ball python on frozen as well as my second corn, so that I can use some of my frozen products. Or at least tell my breeding mice trio to hurry the cows up.
:]