No more than six choices to a screen. Use a touchscreen and big buttons. Use audio - but not in the attract loop. Don't make 'em drill down too far. Everything changes - so should your kiosk.
People forget - automate the update process.
Put paper in the printer - clean the screen. It must be working to work - buy excellent equipment. Accuracy is the only thing more important than speed. If they must wait - show them a progress bar. Don't compete with reality.