Have you looked into Ubiquiti equipment? They’re generally pretty solid, and might have everything you need.

Nowhere - the female end of the cord is what goes in the recess.

I’ve always wondered, does the ear experience additional, unheard “loudness” when using ANC?

Absolutely! Biometrics are at best a username, not a password.

Yep, you just have to set Keep as your default note service in the Google Assistant settings.

Shared notes in Keep sync very quickly in my experience as long as you have a reasonable internet connection.