1) where is the navigation DVD located for updates?
2) has anyone figured out a permanent (not temporary one time) solution to the annoying safety feature which blocks using the navi unit?

 

The navigation DVD slot is behind the clock face. The pin tool to remove the clock face should be in your toolkit in the trunk.

Prestigious Society sells a device to enable all features, including entering navigation addresses while driving. If I recall correctly, it's rather pricey at around $300, but I've read mostly positive comments about it here.