[Zope] Zope/Upgrading & Change Management: Suggestions?

This is a basic question, but I'd like to hear some suggestions about fast, easy, and SAFE ways to do upgrading with zope and related products. What methods do you recommend? 1. What are some gotchas to be careful about? Where do the difficulties usually occur? 2. How can you ensure that you can revert back to the previous install? 3. How can I check for dependencies before doing an upgrade/install? 4. Is it necessary to backup the Data.fs everytime you update/upgrade things? 5. How do you keep a log of upgrades/patches? At the moment, I don't have a test/staging machine, so I'm doing changes on a "live machine." (That is not good, and it will soon change). Thanks. Robert Nagle