Sat Nav unit
 

Hi new to here so going to keep my question simple, I have a 2007 A4 S-line Quattro with the Concert Sterao double din unit now I want to upgrade to the Audi Sat nav RSNE (what ever that means) unit however not sure whats involved also need to be sure i have a can-bus model. I have stearing wheel controls to unit functions, volume ect.
Anyone throw any light on this