Do you put water under the crock when you use a crock-pot?

No

The dish on the inside of the crock pot is normally oven safe when it is removed from the electrical part of the crock pot. Obviously the electrical unit itself is not. If the dish is not removable...

They are great for keeping one pot meals warm and for slow cooking. You can put a stew, soup of even meatballs and sauce on before you go to work and have the meal ready when you get home.

Yes, but not to fry. What do you mean by grease? Are you talking of the kind of grease used in axles? Or the kind on bicycle chains? Then no, you can't. If you mean grease as in "oil" or "fat"...

you plug it in and turn it on and put your meat in it and cook it. sheesh.