the combination meter will have the miles saved on it from the vehicle it came out of, so you would have to either find one with mileage close to yours or have a dealer program it.
the swap it out it not hard at all. the meter is plug and play.
also some meters are designed with models that have the ICC or intelligent cruise control. if your car does not have this and you install a meter that is designed for ICC, you could get false error codes thrown at you from the ECM because the CAN system, the computer system the car uses, EXPECTS to get this ICC info from other parts on the car since the meter is an ICC meter and if you dont have those other sensors (and you wont on an NON ICC car), you can get these codes.
so be aware of which cluster you get should you go used.