I'm considering going from 2004 non-navi to navi. Can you mix compnents, like a head unit out of a 2008 and a DVD out of a 2004/5/6/7/8? Or a DVD out of a different Acura/Honda, so long as it is an Alpine unit?

I have been reading that there are differneces in the discs.

Also adding the steering wheel controls, is anything prewired from the steering wheel to the head unit, or the bluetooth unit in the console?

tia