Paul - The most helpful video I found on google hangouts live recording
How-to Record Google Hangouts Video
Others have better information on each individual step, or list more options and how to optimize them. This one touched everything I needed.
EDIT - *FINALLY* found an app to record from bluetooth headset. The noise cancelling is not as good as Google Hangouts Live, but recording from the headset instead of from the microphone is quite important
Bluetooth Voice Recorder by 0alex - free - and you only need to configure 'normal mode' and 'prefer bluetooth'. Works OK and I'll be using it as it does not require internet bandwidth .. my internet is slow and my wireless coverage is a bit spotty in the garage.