[Opinion / Advice] Multsite – Superadmin and User Roles Access & Permissions Management

I’m in a project that involving multisite environment where subsites are for country basic.

I wish to accomplish few objectives and seeking opinions/advices from all:

1. Is it necessary to have more than 1 superadmin for the multisite? If yes, possible to have other superadmin that have lesser capabilities from the “owner”? If yes, how?

2. What’s the best plugin to alter the backend admin menu (topbar) and backend menu (sidebar)?
*I know “Branda Pro” can do the trick but I observed when comes to LARGE (more than 50 items), Branda Pro will be laggy; I observed “Admin Menu Editor” consider one of the best choice from my personal opinion

3. Is the plugin “User Role Editor” is consider the best and most stable to alter user roles (including add new roles, and set permission for new plugin installed), for Multisite environment.
*anyone been using User Role Editor with heavy-usage and go through major WordPress Upgrades and Plugins Upgrades for years without major issue? I presume altering user roles might need to do quick fix as per major upgrades of WordPress or plugins, if any

4. IF (2) and (3) above = plugin I mentioned, will both plugins (Admin Menu Editor + User Role Editor) work fine without major conflict? Any experience on large, multisite with both plugins above so far?
*large = total WP website around 200GB++ (with DB & Media) and monthly unique users around 200K;

Thank you for your effort to READ and sharing your opinion/experience/advice :)