You should only have to put down a deposit to order the car. That has always been the case for me.
There is a huge difference between the standard audio and the premium audio.
I have a standard and the i drive navigation, and I have never accidentally hit the idrive button when shifting.
2010 Z4 35i - Orion Silver, Ivory white extended leather, anthracite trim, premium pkg, sport pkg, premium sound pkg, cold weather pkg, navigation, 6 sp manual
2006 Z4 30i - Monaco Blue, beige leather
2003 Z4 2.5- Sterling Gray, black leather
1998 Z3 2.8 - Bright Red, black leather