The ES-8 needs to come in early on, too...not only so you can start exploring how to integrate Silent Way or Volta into the DAW, but so you can also determine if you want to add an output expander for more CV/gate/trig control as well. So, that and everything left of the RCD. As for an audio interface, since the ES-8 can feed audio at modular levels, you can go with something simpler; my suggestion would be a Happy Nerding Isolator, because with all of this odd interconnection, having transformer isolation on the analog audio outs might be advantageous to help avoid ground loop issues.