Your car currently has four plugs in the ECU box that interface with the car, DBW cars have 5, however the pinouts on the four you have match up perfectly with the pinouts on 4 of the DBW plugs (assuming the S4 loom is the same as the 1.8T stuff i've been looking at), and the extra plug just needs to be added for the throttle sensor and the brake and clutch switches.
You will need to swap out the throttle pedal, and the big alloy bracket that everything attaches to by the looks of it, to take the electronic pedal. Otherwise it looks pretty plug-and-play.