hi
A pool is an aggregation of unit resources to be planned as a single resource. When you allocate resources to the pool you define its capacity on one or several periods. Then you will plan the pool as a usual resource with its constraints given considering itself the resources's constraints. Please read the friendly usuer manual about pool.

ProjeQtOr does not manage earned value yet.
But you can get project variance through report "S-curve chart".
You'll need to define a baseline (the reference for the variance) to have it work.