1. 2008.
2. No, but it can support Agile methods.
3. By providing unit tests and being a key component in pipelines.
4. Integration tests are crucial to see whether your infrastructural changes did indeed work as intended.
5. Multiple dependencies need to updated with every build. Dependency management is important in order to always have the correct dependencies ready at build time without manual intervention.
6. Separating configurations from input data makes codified infrastructure transportable between multiple environments.