Dension 500 MOST + BTA1500 Blue Module

Hi I have a 1999 Mercedes S320 with CD stacker in the rear (which doesn't work)
and am looking at purchasing Dension Gateway 500 MOST + Dension BTA1500 Bluetooth Module
so as I can use my iPhone 4 with all functions through the vehicles head unit.
Are these Dension units compatible with what I have? As I don't want to buy something and not have it work.
Also do you supply the iPhone cradle/charger with these units?
and am looking at purchasing Dension Gateway 500 MOST + Dension BTA1500 Bluetooth Module
so as I can use my iPhone 4 with all functions through the vehicles head unit.
Are these Dension units compatible with what I have? As I don't want to buy something and not have it work.
Also do you supply the iPhone cradle/charger with these units?