Aftermarket Radio Interface

I'm considering installing an aftermarket nav system, and I'm wondering if anybody has experience with the GMos044 interface.

• Does it retain functionality of the cars built-in microphone for bluetooth? If not, is there a workaround other than installing another mic?
• With the correct adapter, are all steering wheel functions (volume, source, talk, mute, hangup etc) retained? (assuming the radio supports it)
• Are the armrest usb and aux plug functions retained? If not, is there a workaround?

Any help or recommendations would be great.


Thanks!