I can't help with the tech side, but I wouldn't worry about it too much. By the time your eldest is 3 he/she will be 100% competent in DVD control, tuning in TV's, debugging computer programs, and will delight in showing you how to work your new iphone.
Actually, on the subject of phones. There are phone apps through which you can control various media devices. It might be possible to utilise such a function in your car.