Hopefully this page will answer your questions!
I'm not sure what it's called, but we use Taxonomy in Flux. It is maintained by John Boyd III.
Because Wikipedia fails at bird taxonomy. TiF is the most up-to-date site I've seen so far. In fact, it was last edited on August 24, 2014!
I see a mistake! Can I change it?
Only if you use TiF. If it's not on TiF, then don't use it.
I see a species that hasn't been added yet! Can I add it?
Of course, as I said above; as long as it's on TiF, it's fine. Make sure you use the proper layout, though.
But [insert name here] uses a different approach!
Well, good for them, but I'll never use it.
Can I see an example?
Can I see a comparison?
Are there any taxons that have all been added?
Of course! Most of the categories are hidden, but you can check this one out if you want to: Taxons that are complete