Help with layers and new parts

its is possible, see Mode / ‘Edit contours’.

no you don’t. Sheetcam will alternate outside vs. inside kerf offset toopaths for shapes/contours on the same Layer. The Operation offset style you select is in reference to the outer most contour(s) of the Layer, then toolpaths alternate to the other side of the inner contours automatically.

that’s a good idea. Should not be problem to do that.

See also- Where to learn Sheetcam