The main difference in with DNX5140 and the DNX6140 is that the 5140 doesn't have built-in bluetooth.
For XM radio you'll need to add the XM module (Kenwood KCA-XM100V) and you'll need to add the XM Card (XM CNP2000) that goes inside the XM100V. Around $90 for both.
In order to maintain steering wheel controls you need to add the PAC SWI-JACK module. Around $42 on Amazon.
The 1/8" in the center console will no longer work. You'll need to add an iPod cable (Kenwood KCA-iP301V) that will allow you to play your ipod and charges it at the same time. Around $28 on Amazon.