Most of your questions are answered in the OptiBPM User Reference in Chapter OptiBPM Layout Designer Functions >> Export, page 335-6. The option to limit the export to 200 vertices exists because some versions of Calma GDSII would not accept polygons with more vertices than this. If the curved shape you want to export has more vertices than that, OptiBPM will divide the shape into more than one polygon, each with fewer than 200 vertices.