Allow a specific member level the ability to change other members' levels?

I am creating a system for a business that will enable them to record jobs and edit them, etc. I'm using a form system (Formidable) and want to use the wpmudev Membership plugin to restrict the access to the pages the forms are on so only this company's staff can access the system.

I will have two levels of users - Staff & Managers.

I want Managers to be able to set up new users in the system. This means they need to be able to set up new accounts and then assign them to the "staff" or "manager" level.

I can see this could be possible by making them a "Membership Admin", however the documentation states that to do this I would have to first make them an administrator of the whole wordpress site, and then make them a Membership admin. I don't want the managers to have full administrative access to the whole site. And I don't want them to see all the settings of the Membership plugin. I just want them to be able to add users, assign users to a role, and disable/delete users.

For setting up users, I think I could put the registration form on a page that is only visible to Managers and on that form have them choose the user level (staff or manager). That way managers can set up new users and assign them to a level.
Q1: Will that work?

Q2: Secondly, I'm not sure how I can allow managers to CHANGE the level of a user after registration, or how to allow a manager to disable a user account. Is there a way I can do that without them seeing all the Wordpress settings?

Q3: Is there a way I can restrict the total number of active users in a membership installation?

Thanks
Josh