Updates and release notes

I'm curious about the update manager and how we can delay possible issues with AV releases and software updates.  I know I can delay software updates (ie, 10.0.7 to 10.0.8) in our update manager by selecting the previous version.  This can delay software updates from rolling out, correct? (right click on server name, View/Edit Configuration, Advanced Tab, Select 1 Previous)  This selection keeps the software from updating to the latest version correct?

That being said, can you not select to use the previous AV definitions update?  I'm thinking out loud here and wondering if this was selected if it would have stopped us from having issues with the update that was released last week.  I know it keeps us a bit behind the AV curve...but would that be a bad thing in the end?  If so, where is that option located?  

Also, I've found the release notes for web appliance updates, http://ca-repo1.sophos.com/docs/ws1000/ws1000/concepts/ReleaseNotes.html 

Is there a similar section for AV, Spam, and other software update release notes? 

Thanks