Adobe Creative Cloud Pro for Teams

Yes. Seats are assigned to a named user in the Admin Console and can be unassigned and reassigned at any time. This is the main operational reason organisations choose the Teams edition over individual subscriptions.

It depends on the count. Around four single applications, All Apps becomes cheaper per user, and it removes the administrative work of tracking who has which application. Below that threshold, single-app subscriptions cost less and we will quote them that way.