3) I have eyepieces at 59X and 87X. I find the 4 stars easily split at 87X, which goes along with the naked eye test. I find the stars also split at 59X, which means that, theoretically, I can resolve objects at a naked eye separation of 2.26'.
I normally can convince myself that I see the split at 60x, there are nights when it has seemed possible at even lower magnifications. But it is definitely a clear split with space between the pairs at 90x and wide open at say 120x.
But this using a scope that itself is not challenged by the split, the pairs are widely separated at the focal plane and in the exit pupil. When one is working at the Dawes limit, double stars are very different objects..
By the way, the Dawes limit for a 5mm aperture is about 23 arc-seconds... According to Skytools 3, the separation of the pairs is 3.5 arc-minutes. This means that for a 5mm aperture optic, i.e. the eye, the epsilon 1 and epsilon 2 are approximately 10 times the Dawes limit, an easy split.
With "easy" splits like the double-double in a 3 or 4 inch scope, relatively low magnifications can be used. But the 2.3 arc-second separation of the pairs is the Dawes limit for a 50mmm scope, to resolve it and see that thin dark line, it takes considerably more than 100x. This is because a Dawes limit split is not well resolved at the focal plane or in the exit pupil.