Bill Tindall, E.Tn.
Is using a pole lathe ergonomically any different than using a motor powered lathe? (I used one at Old Salem and all I remember was it was too high for me. It did not stand out that my hands were in a "natural" position at any different height than on my lathe. Well, I do remember it was like chewing gum, rubbing your belly and hopping on one foot. )

If not, these questions can be answered by visiting the Turning Forum, or someone with a lathe. For me, on a motor powered lathe, the height of the centers is critical with some tolerance. I have used lathes where I stood on a platform to get higher and more relaxed.

The other questions are dependent variables fixed by the height of the centers and what swing you desire.