Good luck. Best advice that I could give you is go with someone to a bigger event, and soak in all the knowledge and how they do things. That is exactly how I got started. Helping out someone who has been doing it for quite a few years. There are many things that you pick up on, that save your butt, that you will never think of.
I have an event the 24 th of August. It will be a smaller event, with around 800-900 people, but I am the only food vender, and all will be coming to me for a meal.
Another thing is, keep things as simple as you can. Is there anyway away from the slaw, being it is your first event, and go to something simple, such as chips? You are going to have your hands full with keeping the meat at right temps, yet keeping the flavor and moisture in it. Unless you do what is stated earlier in the post, is to package the slaw in foam containers prior.
The event I am doing, I am keeping it really simple. Chips, beans, pulled pork. Beans will stay in the warming box of my trailer pit, pork in a roaster after it is pulled off the smoker and pulled, chips are ready to go straight out of the box.
Are you responsible for drinks as well?
Edit: Just saw that you are offering drinks, and I would take the advice of others and do tea and lemonade. That is where your best profit margin is.