Hi although I'm not keeping anything at the moment that needs crickets I have used crickets on and off for about 15 years.
Gutloading is easy to do yet I think many people over see it and then feed the crickets out to their critters having very little nutritional value!
A piece of carrot or equivalent should be in with the crickets all the time. This will generally give them enough moisture and food. I also had instead of water I used thin slices of oranges for them to drink and eat. This will keep your crickets alive but are they actually "gut loaded" at the time you go to feed them?
When I knew I was going to feed my frogs, dragons etc approximately an hour before feeding I'd make up salads with different veggies and fruits. I would change these items to vary what the crickets ate which then in turn the reptiles would get something different also. I also provided in with these salad mixes about a teaspoon or two of insectivore mix and calcium/multivitamin powder which when mixed the crickets would eat also which saved dusting! Between half an hour to an hour I'd then feed out the crickets. You could see what crickets had eaten what with the couloirs of their poo or if a dragon had burst one open!
Breeding crickets is easy! The hard part is giving them enough space and the right heat requirements to get them to a size you need to use. To breed I used peat moss soaked in water then rung out just like you'd do to a face washer. Place a tub (old cricket container) works great in with your adults. The females will almost instantly start laying. Females are the ones with the big spike at their bum, this is an egg laying tube which they stick into the peat moss laying heaps of eggs. Once you have a sufficient amount of eggs laid put the lid on the container and put them somewhere around 30 C and in two weeks pin heads! Soon as you see them hatching take the lid off and place the tub into a large cricket tub where you'll grow them up. I found once you had hundreds of them hatched you could just blow gently over the tub to get the majority of them out into the larger tub.
Hope this helps