Glad to hear it is working to your liking! As for the name of the sound devices they are names that I have set myself. You can do that under Windows Start button, select Settings, select System and then Sound. There you have the option of naming your different sound-out-put devices, like headphones or VR headsets. Make sure that WRM is active before doing so, otherwise your VR headset will not show up.
As for nircmd i would suggest putting in a "timeout /t 5" in your .cmd file after it starts Steam VR for your VR option. I have found that WRM and Steam VR takes a bit of time to start up which makes the VR headset not being set as default sound device quick enough. That in turn means that the nircmd command in the file gets executed but have no effect since it cannot find the device.
Cheers