Noob Disco Owner

Hi everyone,
I bought a 1999 Disco TD5 at the weekend and wanted to say thanks for all the help I got from searching these forums.
I have a couple of noob questions which I'm sure someone can probably help with:
1. My car has a button to raise the suspension but other than a brief whirring sound when I press it nothing happens. When I look underneath I clearly see coil springs does this mean it's had a coil spring conversion which explains why the button does nothing?
2. It has the Harman Kardon audio which looks to be the Alpine R909 head unit. In the centre cubby box are cables for an iPod, usb and 3.5mm jack but I can't see how to switch the head unit to an aux input. The CD changer still works btw. Any ideas before I pull it apart to trace the wires?
3. Probably a long shot, but just in front of the rear view mirror is a red rocker switch which looks after-market. It doesn't appear to do anything but wondered if there's anything obvious you'd put up here. I know the car had a disabled owner previously and I wonder if it might be related?

Thanks for any help you can offer
Brian

Perhaps the SLS option ahsn't been fully turned off within the BCU/ECU? The compressor is still underneath mine, but she's had a coil conversion done in the past and the button doesn't even cause a whirring sound