Typically you have to use their paperwork because it has already been approved as to form by the production company and the insurance company. If they don't have paperwork you can just make up something simple outlining where, when, what they will be doing, how long, compensation, insurance, transportation, etc. Included in their paperwork is usually some kind of release allowing them to use the images any way they want. All of this should be done in advance so there is no pressure the day of.