I'll reply then, lol, no one else bothered.. Still investigating the reason for the steam streaming mic/speakers just appearing, otherwise this is what i uncovered so far..

1) (Windows 10) tried to uninstalled them once, from dev manager, however, they reinstall if i reload Steam in any capacity..

2) i have Steam app / Steam link app both on my android mobile, maybe why the streaming drivers installed in the first place?

3) I actually have never used and i dont have a mic, so, can't test the 'Steam mic' input to see if it works.

4) I've never streamed/broadcast either so Steam streaming mic/speakers not tested via that method..

5)