Ranger Rover Supercharged Questions

Hello, has someone experienced with a Range Rover Supercharged BJ 2005 ? I plan to get one of these and then have it converted to auto gas. Have now come to know that there should be terrain tyres for 19″ rims (which the RRS is allowed to drive). What kind of navigation is installed in the RRS (manufacturer, type) ? Is there still the possibility to connect audoi/video with? Upgrade possibilities, possibly winch? What is to be paid attention to with such a used one when buying ? Thank you and greeting, Stefan