Instead of buying those expensive stones, just go to your local home store and buy some unglazed floortile. They work just as good at a fraction of the cost.
I only use cornmeal on breads and the likes but never for cookies or meat. They provide their own grease when cooking. I dont see any harm in spraying it but always wipe down when done while it is warm when you are done with cookies.
I love mine! They are the next best thing besides my Lodge cookwares!
After they are seasoned, there's no need to use cooking spray or cornmeal. I bake cookies directly on the stone and the bottoms come out like the store-bought ones - not dark on the bottoms.
I use my stones for everything except fish. The reason I don't is that I'm afraid the fish odor will be picked up by the porous stone.