It depends on the audio device you have. Most probably, the second configuration will be UAC3 if the device is UAC3-compliant.
You can cat the value of the bConfigurationValue before changing it to 1 and then write back the same value to set to UAC3 configuration.
Please note that the device should be UAC3-compliant for UAC3 configuration to work.
And yes, you need to enable adb for this purpose. ADB is enabled by default in Celadon. You need a type-A to type-A USB cable to connect the NUC to host machine.
The device mode port depends on the NUC model which you are using. If you can tell us the NUC model, we can check and tell which port to use.