Each rabbit will need their own cage, they don't do well together, to much of a chance of fighting, or chewing on each others fur, which would not be good for showing. A good quality feed, not anything you can buy at
walmart or a pet store with seeds or stuff in it, that stuff it first off, old, second, poor quality. Then they need hay to munch on, or another type of fiber that several rabbit breeders have recently told me they are using is plain cheerios. A handful a week or a few a day, my buns love them. They need protection for the weather, so where to get out of the wind, rain, snow and sun. So a roof and at least a couple of sides, or inside a building with good ventilation. Heat will kill a rabbit quicker than cold. So when it is hot, plenty of fresh water, even frozen water bottles will help.
To show, trim nails, make sure the inside of their ears are clean. Sometimes their need to be wiped down with a wet wipe for stray hairs or little stains. Cornstarch can help with small stains too. Holding them often and working the showmanship steps helps get used to being handled and makes it easier when you are showing them. Treats are fine, in moderation. Careful of diarrhea, it is deadly to bunnies. If they get it, stop whatever treat immediately, offer hay and oats to stop the diarrhea.
A great book to have is ARBA Standard of Perfection, this will really help with showmanship, as there is tons of info on different breeds, rabbits in general, health, the different types of fur, body types, eye colors, number of teeth, reproduction, etc. and this is the type of questions they will ask you in showmanship.