I'm going to respond to this one, just because it's the most straightforward.
We're explicitly told this in the books:
*"Now, you must learn to compare your strength to that of every sister you meet. In time, it will become second nature, and you will do it without thought, but you must be very careful until you reach that point. If another sister stands higher than you in the Power, whatever her Ajah, you must defer to her. The higher she stands above you, the greater your deference…it works the other way around as well, of course, but remember that it doesn't apply if your Ajah or the Tower has set someone above you. If you're attached to an embassy, for example, you obey the Tower's emissary as you would me [their Ajah Head], if she was barely allowed to test for Accepted.” (from New Spring, Entering Home - Eadyth talking to Moiraine and Siuan about deference)
We also see Moiraine apply this; while strength is the primary consideration, a Sister also took into account their rank in the Tower:
*Without her Keeper’s stole, Duhara would have had to jump when Moiraine snapped her fingers, should she have chosen to. (from New Spring, Changes)
We also see that Elaida is stronger than Meilyn so had no need to defer, but still bowed her head to the older woman in New Spring, The Human Heart. While it's possible that Elaida hadn't reached her full potential, it's also likely that she would have been put down abruptly if she thought she could run around ignoring Sisters who were quite strong, and older than her.
While we've certainly seen stronger Sisters throwing their weight around, we are seeing this through the lens of extraordinary times. Those instances are worthy of comment, because while they are capable
Certainly when the Tower or the Ajah has given another authority deference is expected when specific to that authority. But that doesn't really happen terribly often. And it's almost always women in the upper tiers of strength who end up with important posts. Aside from the Ebu Dar Ambassadors from Salidar I don't think we've ever seen weaker women in a position of authority. Duhara was fairly strong p, even if she was well below Moiraine.
Elaida was not stronger than Meyeln she was bowing her head in deference to a significantly stronger Sister. Cadsuane tells us that after herself Myelen and Kerene were next before a sharp drop to Elaida/Lelaine/Romanda/Moiraine/Siuan. And we're told in that same scene of Elaida deferring that she doesn't defere to any other Sisters.