Hi can anyone help?

I am considering changing my factory fitted audio unit, so that I can install my JVC audio unit which means that I will be able to plug my IPOD into my car's system.

Does anyone know if by changing my audio unit, if it will render my steeringwheel controls inoperable?

You will need a JVC to ford steering stalk control adaptor. There are some on eBay but they look they are for the later model Focus's. You should be able to find one.