You can have both server- and database-level firewall IP rules, and they exist independently. An IP can exist in a database rule and not a server rule, and the user would have access to the specific database and not all databases on the server. Refer to Microsoft Doc:

https://docs.microsoft.com/en-us/azure/azure-sql/database/firewall-configure

ELT is a more scalable approach, because the data is transformed after it's loaded into the cloud database.

The most common type of ID field is a sequential number that starts from 1, managed by the database itself. This is to ensure each row is unique and can be addressed by a unique number. A customer name would make a terrible ID field as it might not be unique. ID fields are typically decimal or hexidecimal numbers.

A matrix visual is a tabular structure that summarizes data.

SQL Server runs T-SQL, while MySQL

DDL is Data Definition Language, and is used for creating data schema elements.

A table represents a unique entity in the real world - such as a customer, an order, or a product.

SQL Server in a virtual machine is the Infrastructure as a Service Model. This requires you to have the expertise to maintain both the server software for patches and upgrades, as well as the operating system underneath. It is one of the easiest ways to migrate your on-prem SQL Server into Azure, as it usually requires very little coding or other changes.

Batching data is processed in groups.