Have a talk with the guys at Comand Online. They install, repair and retrofit all the Comand models and have extensive knowledge on what you are asking.
Media interface - press the disk button until it says Media interface on the screen or select Media interface from the audio menu
DAB is either under the FM selection at the bottom of the screen or you can get to it by repeatedly pressing the 'RADIO' button. depends on your firmware revision and option list.