Construct Plane from 2 Circles, Points, or Planes

Construct Plane from 2 Circles, Points, or Planes

1a) When constructing a plane is it safe to assume the plane constructed from 2 points or 2 circles is normal to the line drawn between those 2 points or circles?

1b) Is the plane center directly between these features?

2a) When constructing a plane between 2 other planes (referenced planes) is the constructed plane parallel to the reference planes?

2b) What if the 2 reference planes are not parallel to each other? If this construction is possible, would the constructed plane be the result of the average of the 2 angles of the referenced planes?

Best Regards,
Cody