To bridge the audio between the Nexus and Car PC, I am simply going to use a 3.5 headphone cable and go from Nexus to Car PC audio. Where the Car PC will simulate 7.1 surround sound, which is what my setup is. I still have to work out the phone and texting part, but I am sure Android has solutions.
Here is where I have questions. I have a serial OBD2 scanner, which has a serial to USB converter. I know for a fact drivers will be none existent. Would it be better to just buy a BT version, but if I do that, how will my phone pair with the Nexus? I also have the HD Radio and TPMS, which I would still like to use. I intend to keep my Car PC, so is there a way I can have them there, but the Nexus somehow accesses it?