Check the rule book, some shows want you to use a cane, pig pipe, pig panel or a pig whip. Whatever the book says, start off with that piece and don't change.
Depending on the weight of your pig that you get there is a pig starter, pig grower and a pig finisher. Talk with your local co-op and see what they have and their suggestions. Compair hog feed to chicken feed, as they grow in age/weight you change (more like weight for pigs).
Our son's pigs had to be on the FFA Blue Tag until 2 wks before the fair and then he'd changed them over to a different feed with a lower protein.
As long as you feed is a balance ration then you don't have to add anything. But for our son's 2 gilts when we put in fresh hay for beeding they like to much on it for a while.
To get son's show gilt out of her pen, I shoved a youth arrow up the pig pipe and stuck the blunt end out so we could pierce a marshmellow at the end so we would not jam it up the pipe. It not easy to clean the inside of that pvc pig pipe, especialy when the temperature is up. Then we moved away from using the marshmellows and gave treats like apples slices after they did something good. For example, if she high tailed it around the pen and came back to him, she got something.
Keep their water fresh and they feed clean (not moldy) and you will grow them. Spend time with them and you will now how they are feeling.
Got to make you laugh, Ruby will go into her pen and shut the main gate on son when she has had enough of a walk with him.
Don't get discourage after your first show. Learn and the press on.