PSD, How did the RCM contacts, especially the traction control relay check out? Kinda hoping you find the problem there because it is relatively easy to fix. If you are convinced the RCM and battery are good then try these:
1) you have said your door locks do not work with the FOB. Can you lock/unlock with the button on the console? If yes replace the batteries in the FOB and move on to #2, if no then check for water in the lower truck well under the styrofoam. Located in that area is the air pump/vacuum that locks the doors and the anti-theft towing module. Either can get corrupted and cause the anti-theft system to activate.
2) You have said you had comms with the SRS and the ECM, and in another post you had no comms through the Data port with all modules; Which is it? If no comms with any module then I suspect the PCM is bad because you have stated that you have power and good grounds at the data port. Thus the PCM is not communicating with anything. If it were good I believe you could test the other modules like the transmission and the Shift Lever Assembly SLA.
3) The SLA could be bad. Have you gotten it wet with a heavy Florida rain or spilled a drink on it? Either will damage the SLA which will prevent the car from starting. It is replaced as a unit. Under $100 on ebay.
4) If it was the park/neutral switch in the transmission giving you trouble you should be able to determine that through the scan tool. That is why I do not think the transmission itself is a problem, because you have no power to even scan the transmission. One other thing sorta rattles my brain and that is the stop light switch under the dash above the peddle. It connects to all sorts of things and particularly the transmission. It also prevents you from moving shift lever out of park, but I haven't heard of it causing all the multiply problems your car displays. I think it is logical to proceed with 1, 2, 3 before trying some other rabbit hole if the RCM indeed checks out okay.
You have the service manual. Troubleshoot procedures are available there.