The question is about how to add USB , bluetooth and ipod.
These used to be add on modules . (well half the question the confusing part)
Also there are several different versions of the modules and now
there is a new version of the radio as well that has bluetooth and
usb ipod already built in .
So the question is how to get usb , iPod and Bluetooth most easily and effectively .
The audio upgrade path is well understood and documented
in this link( but usb and ipod is confusing)
http://www.e90post.com/forums/showthread.php?t=641323
The ipod usb bluetooth solution gets more convoluted on a daily basis.
So if you have a pre 09 pro head unit the answers may be different for ipod usb and bluetooth
if you have a TCU ,mulf , mulf2 , ulf or want to add the new head unit.
all require hardware and programming from what I can tell.