several Talend Administration Center applications: one in the Development environment, one in the QA environment and one in the Production environment to retrieve the artifacts,
an execution server, to deploy and execute the Jobs,
one single Talend Artifact Repository (Nexus or Artifactory) to store artifact items in the snapshots (QA) and releases (Production) repositories.
For more information on the development cycles, see Implementation with Talend.
The generation step is indeed skipped as Talend Administration Center is able to retrieve pre-generated Jobs from archive files. The Talend CommandLine application is thus no longer needed.
Likewise, the Production environment does not require to be linked to GIT as the artifacts that were pre-generated in the previous environments can be imported and executed in a "no-storage" project.
Best practice: Once a feature is released or a bug is fixed, the best practice is to use GIT branches and tags to record this change of status. They are used to identify a specific version of a project at a given time, for example the feature that has been developed, tested and validated, and to identify the environment used to make the feature work (CommandLine/artifact versions, project properties etc.).