DSXchange

Job control routines are stored in Repository database tables. Thus they are not amenable to "conventional" source code control systems. Of course you can make your own arrangements, typically by checking in and out an export of the batch/job sequence.

Since a project can only be at one version, and can not readily be regressed, you do not need separate versions. If you want to keep your 7.1 versions, export them.

I don't think they are backward compatible. If you create a project in 7.5 I don't think you can go back to 7.1. It complained when I tried it.

Version Control works well and is included with DataStage. It will keep older versions so you could roll back to an older version. It does not have a diff. It will promote a job. So you can initialize from DEV and then promote to test and then production.