Alright. on to some basic Data Warehousing... What is ER Model? What's the goal of such models?

How would you describe what the contents of your data warehouse are and how it is designed into tables?

You will need an entity relationship diagram to draw out your different facts and relate them to their corresponding dimensions. The way to do that is in an ER model.

The Entity Relationship model shows the relationships between your data structures. It also allow you to express the normality of the data in a visual manner. The trouble is, with a large relational data warehouse, an ER model can be extremely large and difficult to read. 

The goal is to understand the data in a visual sense, however, because of the size limitation it is best to concentrate on the tables you are interested in. This will make the diagram clearer and the reduce the running time of your model generation tool. 

The people who mostly use these models are the engineers themselves, there is very little upward reporting value to a non technical individual.

Entity Relation Model To draw the scheme .