BI 4.1- Increment versions of the Webi report into CMC and being able to roll back

Scenarios: accidental report deletions, multi user report developments and getting back to someone's good version that was there etc.

Hi experts, please help me answer below questions

1. when do I increment the version and HOW to do it?

2. how to rollback to previous version?

3. Any document that outlines the entire strategy from start to finish.  What things need to be implemented?  What new procedures will developers do and how the BI team processes will be affected?

Any solutions or documents will be quite appreciated

Thanks, Kris