I have an N-1. To respond to this question "When using nav, the DVD has to be in the player?? When the DVDs are in, is your only music option am/fm? If you have an Ipod interface, is that active as well? No MP3 CDs? "
You can put the nav dvd in, set it to where you want to go, and than take it out and listen to whatever you want. With the dvd in you can listen to fm/am/ or satelite radio. I always drive with my dvd disc in and i listen to sirius radio. Cant answer the ipod question.
Hope this helps