Bluetooth car-audio

Hi, I have never had a car-audio supporting bluetooth,
so I have no idea how does it work... Tell me, please,
does it just detect new call and mute itself or can it
be used in place of a wireless headset, I mean I could
listen to phone over radio speakers and use a microphone
in the car audio to talk ?

Also, what would be your recomendation for a nice car
audio with a bluetooth support to buy and replace in camry ?
I need it also have front socket to plug in my iPod.
Thanks!