I did not go with the bluetooth option as I didn't think I would need that functionality. You will need to build the harnesses but the detailed pinouts are on Radensb Github site at
https://github.com/radensb/eZ_Navi-Delete/wiki. The A/C harness is a pretty simple cable that connects the base model A/C physical controls to the car so that the the unit detects ignition, can power the A/C control lights and send necessary signals to the car's A/C system.
The main car harness is a larger and more complex cable that communicates a variety of signals through the board; you can see the list of them on the Github site. I did not have the expertise to build the cables myself but fortunately had a friend who does and could help me with the project. The cables were the only step that I needed outside help with (besides purchasing the board, of course).