In 2004 Impala, do I have rotor or drums?

The best way to answer you question is to tell you to take the vehicle to your nearest dealer and inquire with the parts dept. I can tell you that on the ffront of your car you have rotors and the brake used on the front is called a pad. Also your vehicle does not have a separate parking brake. It is the same as the regular rear brake no matter which type of brakes you have on the back.

front there are rotors and pads and back probably the same but need engine size and model

you have rotors usually only the front rotrs and pads need replacing, if you haven't let the brakes go to the point of rotor warpage you can get away with just replacing the front pads. If a pulsation is detected when applying the brakes at higher speeds the rotors should be replaced