Add-a-phase questions

1. I hate to 'bug' my electrician friends, but I can't remember what type of 3 phase is in my alley, either Delta, or Wye?

I know in the commerical district there is available 3 phase, that is different from what is in my residential alley. At one time a neighboring city even had DC in the alley for the elevators.

1. I was always under the impression that the 'wild leg' was generated between any 'Wye' phase leg, and the ground. Is that correct?
2. And this wild leg voltage was approx 1.6 times the voltage, of the leg taken to ground. ?????
3. My biggest question is, "Do the motors on a 17HP add-a-phase, both have to be the same as the 3 phase in the alley"?
4. And have the same windings as the actual 3 phase motor they may be driving?
5. And the same windings as the transformer windings in a welding machine they may be driving?
6. I imagine both 'add-a-phase' motors, have to have the same windings, either Delta or Wye?

I saw a mention in one of the recent group articles about Delta, but now I cannot relocate that article, hence these questions. Sorry thanks all.