Plugin to allow Members to manage other Members

I am looking to set up a new site for my company that would be a “portal” for my employees across the country to log in and see what’s going on in the company, register to attend events, and take periodic training exams.

I want to set that all up, but first I need to structure the memberships to my site (the site will be locked from public view) like I’ve structured my company with managers over other employees. I’m posting because I haven’t been able to find a plugin to do that. Here’s more of what I’m looking for:

I, the site admin, need to be over some regional managers, they need to be over some district managers, and they need to be over sales reps. The idea is that the sales rep can see his own activity, the district manager can only see his own and his sales rep’s activity (including exam scores), the regional manager to see everyone under him and myself to see everyone.

Where it’s for my employees I don’t want to charge for memberships.

Currently I have 4 levels, but I may have more down the road, so being able to add more is important.

I’m willing to pay for a plugin that does this, but haven’t found one that looks like it does this (I may be searching for the wrong terms).

Does anyone know of a plugin that can perform that for me?

As an extra side note, does anyone know of a good exam/quiz plugin that will allow my employees to take tests and allow their supervisor to see their scores?

Thanks for the help.