I had these same requirments, and found all sorts of options which replace the CD changer and present via the head unit.
The problem I found with them all is that none support address book properly, voice commands or mute radio when a call comes in. (Needs to be on CDC)
To top all that off, they where very expensive and difficult to find. Cheapest I found was a £300 unit, and that had no address book of any kind.
In the end, I went with a Parrot MKi9100.
Now that covers ALL the Bluetooth options in terms of radio mute, voice reco and quality.
On the A2DP side, it normally just mutes the radio and uses its own amp, which results in terrible quality sound.
However it does have a line out, and I soldered a 3.5mm jack to this and just plug it into the AUX socket.
The down side is its a 2 step process starting BT A2DP music. 1- start it on the MKi9100 and 2- select AUX in.
Still a LOT quicker than fiddling with any cables.
It works very very well with my Galaxy S3, and I hardly ever listen to the radio now.
Jump in the car, hit "Bluetooth audio" (leave the radio on Aux all the time) and drive off.
Tunes start playing straight away.
All that for just £120. (And that was on the high street. Im sure online you can find it for less)
I didn't choose this option, but you can also buy a unit (Unkia I think its called) which will use the steering wheel controls. However I found the included remote to be more than enough.
All in all, its not quite the OEM look I was after, but for the cost and how well the solution works it cannot be beaten if you want Bluetooth calls with Voice and A2DP
EDIT: forgot to add, it also provides you with another Line-In connector (handy when my wife is in the car and wants to play music) and a USB connector for USB playback.