Various sockets and wrenches are necessary to remove the brake caliper from its mounting bracket and the mounting bracket from the steering knuckle in order to remove the rotor. There is also a special tool necessary to push the pistons back into the calipers before installing the new brake shoes. Any rust or debris on the hub surface should be cleaned with a wire brush to help insure that the new rotor sits flat on the hub. All fasteners should be torqued to the proper specification as they are reinstall. Please consider that the brakes are probably the most critical safety system on your 2002 Cadillac DeVille and it may be a better idea to have a professional repair your brakes that trying to do it your self knowing that you are unfamiliar with the tools necessary to perform the job.