#1 - That is what your VCS history is for.
#2 - Choose good variable names and you don't need these comments.
#3 - Use built-time templating to do variable substitution in your CSS as part of your build process.
#4 - Nonsense.
#5 - Nonsense / That is what your VCS is for.
Clearly, CSS is crying out for a good IDE. Not the Dreamweaver/WYSIWYG variety, but serious text editing features that are pretty standard to programming IDEs.
Which would you rather have: Gecko/Webkit embedded in an Emacs buffer, or an Emacs/Vim buffer embedded in Firefox? I've seen some stabs at both, but neither really Done Right.
Probably the latter. Having Firebug IN the IDE would be invaluable and (r)evolutionary. A lot of the times I 'develop' by writing CSS in Firebug, then copy-and-paste the result into the actual CSS file.
Hm. That means I want a WYSIWYG, actually. Time to fork Firebug?