Hi,
I feed all of mine defrosted food so I really can't give you any information on live feeding.
Its worth asking when your buying your snake what it's eating and see if they have any that are eating defrosted as it's a lot easier to have a sealed tub of frozen food in the freezer than having to go pick up live food every week. But I certainly wouldnt let it's diet be the deciding thing that stops your son getting the particular snake he wants - sometimes they can be converted from live to frozen/thawed.
The general concensus seems to be there is no need to feed in a seperate enclosure and, in fact, the stress of being moved can discourage the snake from eating. Ball pythons are secretive snakes on the whole and changes can throw them.
The care sheet covers pretty much all the information on husbandry but since all snakes can be individuals to a certain extent it depends a lot on your final choice of snake.
And , as an extra warning, if you do feed live it's important to watch to make sure the process goes smoothly. I'm sure someone who feeds live routinely will be along to answer any specific questions about it but everyone seems to agree the mouse/rat should never be left in the tank unattended.
dr del