@birdair said:

b) Why some curves lines (ellipses) looks faceted... can fix that little problem... how?

You can always take your curve and convert it to FSpline or Cubic Bezier to get more intermediate points (you need first to convert it to a Polyline). But I am not sure it can give always the same best results as to think of the number of segments in the first place when you create the curve, as RunnerPack says.

Fredo