What equipment do you have available? What type of vending set up will you have? For butts, keep them whole as long as possible. Even if you don't use them right away. I reheat my whole butts to over 160*F and hole that way until I am ready to use them. When you reheat the butts, save the drippings from the pan for moisture later.
Ribs are tricky. For a large event, I would cook as many ahead as you can hold in refrigeration and just reheat on a smoker at the event.
Coleslaw will depend on your equipment and setup.
If you need help on a setup, PM me. I vend at farmers markets on a small scale, but have done several events with 30,000+ people.
Team: Pyle's BBQ; Good-One "Trail Boss" 60T; Homemade rig; 22" Weber Kettle w/rotisserie ring; Big A$$ Rotisserie; BGE-Small; Weber Kettle Gold, Weber OTS, New Braunfels offset smoker.
Saddles BBQ Bistro