HR Dashboard - Headcount Tab - Where to find data, how to change colors, and how to change filters?

On the out-of-the-box HR Dashboard (Reporting > HR Dashboard tile), is it possible to know the reason the colors are different for the same categories and if they can be changed?

For the filters, we are asking if that when a Supervisor Level is selected, the downstream Supervisor Level list can be reduced to only show the Supervisor Levels reporting to that person. For example, if I am a Supervisor Level 1 and have 5 direct reports, we would like to only see the Supervisor Level 2 with the 5 direct reports to choose. Currently, I would see all Supervisor Level 2 options and not just the ones under the selected manager in Supervisor Level 1.