P: Super Resolution - variable output size

If the file became too big for the printing lab, you really did not need to do any super resolution at all. You really only need superresolution for billboard sized prints for it to make sense or when you cropped your image to a tiny size. When you cropped and superressed the file you send a printer will still be smallish since a jpeg (almost always a jpeg is more than good enough for printing) or tiff will be reasonable size.

Superresolution is almost never distinguishable from just using the scaling algorithms in export in prints. It is a neat feature but rarely useful except as said in that highly cropped or image from an old low res camera example.