Visible crew/equipment: When Lois pulls up to the house where the blackout was traced to, she hears some music coming from the boat down at the dock. As the camera pans upwards over the car, as she steps out, the whole camera and a crew member are reflected in the side of the car.
Visible crew/equipment: In the scene where Martha Kent investigates the crystal ship, there is a fuzzy outline of a crew member behind the truck.
Answer: There are two stories: a) the suit was made by Martha Kent from the blankets which came with Superman when he was a child and these blankets got superstrenght from the sun too. b) Superman generates an aura which protects him and his suit against such forces. Both stories can be true: either the suit itself is weakend by the kryptonite or Superman's aura was weakend by it. Currently it is said that the blanket-story is the correct one. Also, they don't actually cut it off him - it appears to open along a predefined line (coupled with someone exclaiming "got it!"), presumably the method Superman uses to get into the suit himself.
Bjoern_Buller