What is the role of consultant has to play if the title is BW administrator? What is his day to day activity and which will be the main focus area for him in which he should be proficient?

BW Administartor - is the person who provides Authorization access to different Roles, Profiles depending upon the requirement. 

For eg. There are two groups of people : Group A and Group B.

  Group A - Manager

  Group B - Developer

Now the Authorization or Access Rights for both the Groups are different.

So for doing this sort of activity.........we required Administrator.