This page in the Manual explains that error code:
https://manual.audacityteam.org/man/error_opening_sound_device.html#codes
WC
It may have.
See if the sound card driver has been updated, and if it has you could try rolling back to the previous version.
Be aware that monitoring via software introduces some delay to what you hear (typically around half a second). For some hardware (such as some USB record players) this delay is unavoidable but not really a problem so long as you are aware of it.
Yes.
Super 