So you don't have to go through all this FX3.1 update ...
0) Make a backup of your \My Flash Disk\*.* including folders to your backup SD card.
1) To remove the nav nag message, you have to replace basically 3 file in the \My Flash Disk\APL1 folder. Download this file "AVIC_F900 v322 nowarn.rar" here http://avic411.com/forum/viewtopic.php?f=34&t=25108, unrar and replace in TestMode.
2) You will either need a SW fix or HW fix to enable passenger (OR YOU!!!) to play video or the GPS during driving. For the SW bypass, you still have to ground a wire I think, read here: http://avic411.com/forum/viewtopic.php?f=34&t=17715&hilit=software+bypass. For HW bypass, there is a picture guide here: http://avic411.com/forum/viewtopic.php?f=34&t=17013.
3) For any other business, just search my friend!
Good lucks.