I'm part of a group that is designing a community center as a senior project. Most of the CAD work that I have done has focused on roads/highways, this is the first building site that I've worked on. I've got everything laid out for the most part, however at this point I'm trying to figure out if there is a way to calculate cut and fill for a site, similar to how you can calculate cut and fill for a corridor. I have the Existing Ground surface set up with imported topo from Google Earth as well as the parcels laid out. Any help would be greatly appreciated! 

The vanilla version of AutoCAD does not understand digital terrain maps.  You'll need AutoCAD Civil 3D to compute earthwork I'm afraid.  More than likely it will be quicker for you to construct cross sections and compute your volumes with end areas.  Pretty much the way we used to do it.Dave.

I am using civil 3D 2012. I went through a tutorial on grading which allowed me to grade the parking lot and around the finished floor elevation. I'm not sure if its the easiest way or best way but it seems to be doing the job. I just need to figure out the earthwork part for grading.

You need to create three (3) surfaces to compute your earthwork; (1) an existing grade surface; (2) a finish grade surface; and (3) a volume surface.  When you create the volume surface you'll be asked which surfaces to use to create it.  You'll select the first two.
 
In a nutshell that's the procedure.  Have fun!
 
Dave.