Re 1. Disagree in certain circumstances:
If thou chooses to sing or play rubato, then assembled company should respect this and NOT try to pull thee into strict timing, and thou should be able to continue to vary thy timing all over the place, as befits the song or tune and thou thinkest best!
(Saw a splendid example of this by fellow Mudcatter, Diva, once, when assembled company tried to sing along to a perfect beat, but she did it her way - the more they tried to pull her into a straight timing the more she rubato'ed to put them off the scent!)