[JWNPlumber]

Burnout, not sure if you could pipe in a drain to a garage floor legally by building code with out some type of grease trap. You may be able to get by with piping the drain into the ground but I would definately check the codes in your area. As far as the walls go a good idea would be the kind of material that your local grocerie store would have up in the meat department or deli area. I have seen it installed and if all of the seems are siliconed up tight you can hose it down.