1. if you brought the f900bt and got the d3 instead, go exchange it for the one that you wanted.
2. im 90% sure that you do need a dis for the navi to work. if you want to watch a movie, you have to take out the navi disk and put in the movie disk.
3. the bypass from a different unit will not work on the D3
link to ur D3 bypass mods- they have a few threads on it
http://avic411.com/index.php?/forum/9-hacksmods/
4. cant help on the update uodate part. i think it only update you with new updated map.
hope this helped