Welcome to the forums.
As you suspect, these topics have been talked about to death. I will give you a quick synopsis, but use the search
Bluetooth is spotty at best. GM only ofically recognises 3 phones that have been retired MANY moons ago. Again search for help with pairing for your phone. It may not ever work correctly.
Muting is hit or miss. For a while, my radio would mute with every incoming call. Now it never mutes unless in the radio screen. When i am listening to a CD, I must stay in the CD screen so if a call comes in, i can pause the music. However, the caller gets an earful of loud music for a few seconds. It sucks but goes back to the overall Bluetooth suckiness of this head.
The sub in this car is a free air woofer. It will never give you that deep bass you are looking for. There were a few threads several months back talking about this. Do a search. A quick fix is to have the trunk full. The more stuff the better the bass will sound. Not practical but it works.
Sorry to beat a dead horse, but search these forums for your answers. There is some great information just a click away.