Surfaces

Labeling Surface Elevations on a Grid

Go to the Annotate Tab<Go to the Labels & Tables Panel<Select the "Add Labels" Menu<Go to "Surface" and then "Spot Elevations on Grid"
Select your surface.
Select your base point (bottom left corner of grid).
Select the grid orientation.
Select the grid spacing.
Select the upper right corner of the grid.
Hit enter if you don't want to change the size or rotation.
Your labels will be created on the C-TOPO-TEXT layer and only where they overlap with the surface.
Reference

Converting Surfaces to 3D Solids

Select your surface to bring up the surface specific ribbon.
Go to the "Surface Tools" Panel<Select the "Extract from Surface" dropdown< Select "Extract Solids from Surface"
In the "Extract Solid from Surface" Menu<Select your surface to extract from<Select the vertical definition (down a depth, to a fixed elevation, to another surface)<Select "insert into current drawing" or "add to new drawing<Select "Create Solid"
In the "3D Modeling" Workspace:
You can "slice" your solid along a straight line to cut it.
You can find it's volume by typing the MASSPROP command.

Filling in Holes in a Surface

Reference