For the new style GM electronics the engine and auto trans are controlled by completely separate modules, you just need to wire a TCM up and tie it into the appropriate circuits to have trans control. This is both an advantage and disadvantage depending on the car setup over the LS1 PCM that had both engine and trans control in 1 module.
Yes, you should change the VIN to be something like 1GN... so that EFILive can pull the appropriate PIDs for logging.