The first questions answer could be achieved by first use "Draw from Coordinates " to place all surveyed points as text in a drawing, the label of the points should be the elevation.
Next step is to drape the text labels onto the surface using "Edit View Surface" finally export the text strings to Excel. You will end up with text labels in Excel with surveyed elevation as text and surface elevation from the Z value. Then it is easy to set up a Excel column with the difference.
I'm sorry but I don't understand the second question.
/Lars