No need to even consider live feeding really. It's just the method I chose. We raise our own feeder rats so it's very convenient for us. Live feeding, frozen/thawed or pre-killed are all good, acceptable methods of feeding ball pythons as is the choice of either mice or rats. Basically it's what works best for you, what you can get a good quality consistent supply of and what in the end the snake will take consistently with a good aggressive feed response.
Just another suggestion (hope you don't mind). Instead of transporting the snake to your friend's store for feeding and then taking it back home, perhaps your friend could drop over after the store closes, bring along "dinner" and help you get used to feeding your snake. Some snakes, if disturbed right after a meal will regurgitate and you really do not want to deal with that hassle. It's a mess and it's also damaging to your snake as they have very strong stomach acids that come up with their undisgested meal.
~~Jo~~