Excellent advice, Toost.
While on this particular subject, it might be a good idea to remember that the scan data more than likely isn't 100% accurate due to measurement error (which is usually small, if the scan operator and machine are worthwhile) and small errors or usage of tolerance in NX for the sake of surface quality may not drastically affect the end part (when it comes to seeing the physical parts side by side). I'd keep the scan data for an envelope reference, making sure as I rebuilt the part, I was "close" to it. Granted, this is all relative to what you're trying to achieve in the end - I just watched a co-worker make minute adjustments to surfaces that resulted in an assembly being off by more than an inch (over a length of 5+ feet), but Toost has you pointed in the right direction - as well as some of the other routes pointed out to you.
For your curves, the fewest number of segments and degree values of 3 (minimum for tangency) or 5 (minimum for curvature) would be the most desired if I am recalling my Shape Studio training correctly. The combs will be invaluable, as Toost as shown. Be prepared to create, refine and recreate - maybe more than one cycle.
Tim Flater
NX Designer