i have a spot of rust on the back hatch above the keyhole, and a spot on the driver side a-pillar.... my nx is white and i was wondering if anyone knows the best paint to buy that will match the closest? and what should i do... sand it all down and paint, or primer first?

If you want to do it right you can go to your local auto paint dealer and they can take a machine up to your car and match your paint.
The machine gives a code that will be exactly what your paint is aged and all.

If you have rust you will need to apply some primer, and then paint it.

You'll need to remove the rust with a grinder, fill it in with body filler, and sand it down, then primer it, then paint it. The rust will come back if you dont remove it all.

~Ryan