1. Anyone faced below issue when using the variable contour when selecting the surface selection for the drive goemetry? What is the issue that causing it?
Non-native geometry and the model rounds aren't necessarily the best in the industry. Best approach, and to machine this with NX's ootb toolpaths, you'll need to add new geometry. Lots of work ahead. Good luck.
Also, this option might be of use to you if you have many parts to make: