Fleet vehicles

Thanks. What I am looking for is to put together a written agreement between company and employee for use of company vehicles. Such as if the ladders are left unlocked at night (company supplies locks and chains) and they are stolen off the truck - who is responsible? Also a written maintenance schedule for the employee to take the truck in for service (company paid), rules for keeping it clean, and vehicle damage liability. I am trying to think of all of the possibilities that may come up with someone driving a truck around with the company name on the side and full of tools I have bought.