It describes the process of evaluating demand forecast accuracy, the pros and cons of different forecast accuracy metrics & the mechanics of each metric.

This template can be used as a model diagnostic to evaluate the fitted model.  There are several metrics available to use as a model diagnostic including R-squared, WMAPE etc

This template is simple enough to calculate MAPE and Absolute accuracy over multiple skus supplied out of one DC.  You need a slight modification to calculate this in a multi-DC environment.