Super admin only in Wp admin are

I know it is possible to restrict dashboard access to admins only in a multisite Wp, but can You also restrict to superadmin only. And a different question. I see the WPMU dashboard plugin use some resurces and to increace speed I consider removing the dashboard plugin. Will is still be possible to upgrade the WPMU plugins from inside Wp, or from a rente service like Wp infinity/ mange Wp?