Hi Brittany!
How fun! I bet you'll do great!
As far as displays, I agree about going vertical. You can go to your local thrift shops and often find great deals on display pieces that maybe just need a coat of paint (or are great as/is!). All of my displays were thrifted and I love that they are unique AND cheap! :)
I would definitely had out business cards or postcards with your products and info, but I wouldn't do a discount code. A good percentage of my orders come from people who originally found me a craft shows, they will come back to shop even without a discount code!
As far as inventory, it's really hard to say for your first one! Once you'll do a few then you'll know better what sells. I'm not sure if this helps or not, but when I have a new bib design, I make 3 of the exact same one. If they all sell at one show, I know I have a winner and I'll bring more next time. So I would at least have 2+ of each design and color combo so you can see a little better what people like. I am always surprised at what sells at craft shows as opposed to online - it's very different!
And my motto always is "You can't sell it if you don't bring it!" So make as much as you can! If it doesn't sell, you have a ton of inventory for next time!
Best of luck!
jesi