The USB port in the center console of my 2014 does provide enough current to charge my Pixel, albeit VERY slowly. If I have an app running on the Pixel while it is plugged in, the battery life diminishes slowly (not enough power from the USB port).Bluetooth audio wasn't added until late 2012. When the Volt was released, the MyLink software wasn't compatible with the Navigation software I think. It took them a year to be able to get MyLink into the Premium Volts.
I don't think anyone else has tried to get Bluetooth audio into a 2012. I just use the Aux input on mine, and that works fine for me.
As far as updating, I believe you just use the USB in the console. Which brings my complaint: Why can't the USB port provide enough power to charge a phone?
My wish is for a second USB port under the dash in the center console.
Read post #11 at https://gm-volt.com/forum/showthread.php?13451-USB-port-not-charging-iPhone to better understand the power available for charging from the USB port.
EDIT: Using a USB adapter plugged into the PTO in the rear passenger cubby should provide enough power to recharge a phone quickly.