Re: keeping crickets alive
Keep em clean & dry in a tote box or aquarium and use a screened top, provide fresh food & water in jar lids or something similar, keep wadded up newspapers &/or egg grates for housing, they need something to climb on and space so as to not puncture each other with their spurs.
You can feed them a piece of potato or fruit, even dry dog food bits and some pet shops have ready made cricket food available in pellet form.
Not disagreeing with Gonefishie, but I've heard, to remove any dead ones as soon as you see them, they supposedly release chemicals upon death that can be toxic to the others