Point 1 is wrong, unless the person drafting you is on the back of your tandem. On a normal bike, they are too far behind you to assist streamlining.
I'll agree with most of the rest but I tend to have a little more concern about not deliberately taking down a wheel sucker. Don't see why people get bent out of shape over people sitting on your wheel for long periods though. Just slow down, ride beside them and engage them in conversation.