Explanation

Box 1: Yes
Like IaaS, PaaS includes infrastructure - servers, storage, and networking - but also middleware, development tools, business intelligence (BI) services, database management systems, and more. PaaS is designed to support the complete web application lifecycle: building, testing, deploying, managing, and updating.
PaaS allows you to avoid the expense and complexity of buying and managing software licenses, the underlying application infrastructure and middleware, container orchestrators such as Kubernetes, or the development tools and other resources Box 2: Yes You manage the applications and services you develop, and the cloud service provider typically manages everything else.

Box 3: No
There really is no way to pause / stop billing for your Azure SQL Database.
Microsoft's official answer "Yes, you can export your database. Delete the Azure SQL database and that will pause billing. Then when you need it you can create a new database and import your previously exported DB."

Reference:
https://docs.microsoft.com/en-us/sql/database-engine/availability-groups/windows/active-secondaries-readable-secondary-replicas-always-on-availability-groups?view=sql-server-ver15