I usually don't feed them until I get to the show, then after the cage is all set up, feed them and put a little water in there. I do NOT keep the water in the cage but offer them water a few times a day.
You don't have to take down the cage/curtains between Sat/Sun so you'll have a little more time Sunday morning.
The litter pan stays in the cage unless they want to "play" in it. If so, take it out unless you want to clean up litter on the bottom of the cage. If they seem to need the pan, then put it in there. Take an extra towel or two in case of accidents.
My cats were more relaxed at 2 day shows - one day shows is harder as its little time to rest between rings. Most times they will start about 1/2 hour or so EARLIER on Sunday as judges need to leave to catch flights home.
Good luck and best wishes
One other helpful hint since you will be showing in different classes - MARK your show schedule (circle) when your cats are listes; eg; Kitten class and Championship AB/SH/Aby or Premiers (SH/AB). That way you know when to pay attention to which ring. Its helpful when showing more then one cat (especially in different classes) to have a helper (spouse, your child, friend, etc.). Many times you will be in 2 different rings at the same time and need to get the cats up there so you don't get a 2nd call and keep everyone waiting.