The edges Drape creates will end up on the current layer. So if you create a temp layer for the drape and set it as active, then you can afterwards select one of the draped edges and Right-Click -> Select -> All On Same Layer. That way you can be 100% sure you get all draped edges.

Youcant import it directly in to SU, but from my very brief research you can import it in to blender, from there you should be able to export it as something SU can read, like 3ds.