> 5. Plugins, plugins, plugins.
> Is there a comprehensive (or at least comprehensible) one-stop list
> of all the best plugins floating around in the plugin-o-shere? Are
> there user reviews on them?
RubyForge and GitHub both have tons o' great stuff.
> Bonus: Is it possible to un-plugin a plugin without leaving litter
> behind? Or do I have to resort to a source code rollback?
If I'm not mistaken, removing a plugin is generally as simple/straight-forward as deleting its directory and contents from the vendor/plugins directory.
> If you have a favorite book, website or back alley for this sort of
> information I'd like to hear about it, even if it's well-known. I'm a
> bit isolated out here, so I don't always know about the stuff all you
> young whippersnappers are up on.
http://peepcode.com - It's completely worth getting a subscription to Peepcode.com, the screencasts are insanely informative.
http://railscasts.com - Ryan Bates has earned a special place in (insert favorite version a good afterlife place here) for his awesome free screencasts on a myriad of Rails topics
http://railsenvy.com/ - Gregg and Jason have a bunch of great presentations/videos about different topics. Gregg's presentation on Active Record was insanely helpful to me.
As I mentioned, this is by no means an exhaustive list, but the links above are all good starting points. :)