Do I need a written agreement and insurance?

Yes, if someone comes into the kitchen with kit and the shoot is not a casual visit. The page states dishes, uses and deadline; extra cover is beside the point for one quiet hour in a room that is already open to the public. Have the venue name, the hour, and who answers if crockery breaks. In Madrid it is agreed in scattered messages and later nobody knows if the photo can be printed. The agreement states the dishes, the uses, and that the menu file is for the venue.