Single Comment

All of the stats I referenced came from the Wikipedia article.
I cannot say whether or not other important stats,
discoverable somewhere on the internet, were not noticed by 
the editors there.

I strongly opinionate your theory must be correct that, 
due to the first move advantage (by white), victories for 
white require fewer moves (on average) than for black.

No matter how important a given number move is, I 
notwithstanding always ascribe the move preceding it to be 
slightly more important because it was critical to making the 
given number move which followed it possible and so forth.  
Moreover, both players normally have many choices.  
Ultimately, the move that precedes all others and cannot 
itself be preceded is the very first move of the game 
(by white).