Pro Sites + Network Enable or Not?

Just to make sure on when to enable or not.

Any plugin I activate network wide will be active on all sites?

If it’s not network enabled, I can enable it for individual sites, using admin dashboard/Sites/ then edit the specific site settings?

If I’m using Pro Site plugin, I would network enable ALL plugins, and then choose which ones are available for all sites, and which premium plugins are available for each paid level?

Same with themes?

Is this correct?