I did some similar upgrades with my new HU. Check it here: 2012 HU/Speaker/Amp Build Log
In your case you will need a few items:
DD bezel - New side pieces to install the HU
PAC Harness adaptor - This will provide acc and constant power and speaker inputs to your new HU
PACSWI - This is your steering wheel interface.
On mine I have a BT HU so it has its' own phone button on it. You can program the wheel function to work with that through the SWI programming.
For Connectivity on the U-Connect, there is a small grey plug (3 wires) in the back of the HU that I did not re-use. That small grey plug I believe is the UConnect plug that grabs info from the HU (not 100% sure) and relays it back to the menu screen. I think you can figure out a way to retain that, but I didn't bother.