RE: Spektrum modules
The 921 and ar9000 work with the 12x and 9303 as you said.
I've not messed with the programming on the 10C or 12z but based on what I know about the 9c it only supports 8 channels in PPM mode. Since the modules require PPM mode to operate I doubt you will see anything more than 8 channels available with Spektrum modules and Futaba transmitters.