USB and ipod shuffle

I have an ipod shuffle, which is the little ipod with inly the 3.5mm output. At the moment it is connected to the car via a 3.5mm jack plug lead. The ipod headphones control the trach selection but clearly this doesn't work when connected to the car. The ipod is connected to the computer at home via the supplied usb to 3.5mm jack lead from Apple.

So my questions are:

Is there a 3.5mm jack lead I can buy that will also emulate the control unit that the headphones use so I can control the tracks when using it in the car?

And if I upgrade my car so it has a USB connection, how will this work with my ipod? Anyone got USB and an ipod shuffle and can tell me how it works - does it connect via the usb and do you get full control of it?

Thanks.