Best stick with rodents for the BP... that's what they eat in the wild. They do not eat eggs, and, in fact, only one type of snake can eat eggs.

As for the kingsnake, I would stick with rodents for him, too. Rodents are the most nutricious food for a snake, and what they will typically eat in the wild (garter snakes are some of the only few that typically eat fish, crickets, and worms... and kings and milks can be cannabilistic, eating other snakes, but, again, best to stick with rodents).