Hi im planning on buying an aftermarket stereo from walmart and yeah i have a few questions. ik that you have to buy the dash kit to put it in and ik you have to buy a stereo oviusly. but when you buy the stereo do you have to buy the wireing that hooks the old car stereo wires up to the new stereo seperate or does it come with it and if it comes with it how do you no ur getting the right one that goes with ur car. and could i got back and hook up a couple of subs and an amp to it later down tthe road ....thanks for ur help