EDITED: Looking for a way to view ALL modifications to a Drupal site's system made via the admin. If possible, I'd like to be able to "roll them" any system changes made, and have the module sorted out any dependencies related to the roll-back, or at least get a clear warning message stating what is going to happen -- or simple state why it's not possible to undo.
There isn't an easy way to do this, since configuration is stored in different places for different things (and modules are pretty much free to store their configuration and content how they please).
I can think of one way to kind of accomplish this:
Build the functionality of your site with Features. The Features module is able to track the configuration of many modules (modules you need may or may not work with it) and then give you a diff of the configuration between the one stored in code and what is currently active. You can then redeploy your site with the original features, and then reimport all the content... I know this sounds messy, but this method might be your best bet if no one else has a different solution.
As an upside then, you've developed your site with Features so you can implement proper revision management.