A:AnswerYes, but only 1 base unit can be used, so the second base can't be used. You'll need to get an accessory charger for the sixth phone. To pair the phones from different sets look in the contents for Add to pair instructions & follow along.
A:AnswerWe entered 77 contacts into our phone’s directory. Those automatically went onto the other two phones regardless of which phone was used to enter those.
For the list of incoming calls (missed ones as well as those answered) we periodically check the list and delete ones we don’t want on there - but any or all can be deleted or saved as you want.