1-3 of 3 Answers
Yes, I have switched back and forth between using only the left and only the right and also shared one of the buds with my daughter while making a call.
No. I gave one to my wife while on a call but we had to be close while speaking so that it will be audible to the person on the other side of the call. We were able to hear them even when we were apart though.
Yes to both questions. But not sure if you can pare L & R with different phones.