CAM-chem output is saved as gridded files.Finite volume simulations use a regular grid.
Time: Instantaneous time saves exactly at the time specificed. Average time saves at the end of the time period. For example a month average of January 1 to 31 will save at midnight on January 31.
Altitude: Vertical layers are sigma hybrid coordinates. You can convert into layer edge or center pressures using the conversion factors (P0, hyam/hyai, hybm/hybi) combined with surface pressure.
Horizontal resolution: Latitude and longitude coordinates are saved and represent center values of the grid box.
A great overview describing CESM output in general and suggesting some options for visualization and analysis can be found in the following lecture notes: