I've lurked on this list for about 6 months now. Basically I've been looking for sources to address questions that I run across as an editor, not as an academic.
I have to comment on Corneli's question and Darnell's answer: the "category system is hopelessly muddled." I can only agree - in 10 years as a pretty active editor, I've never figured out what can be done using the present categorization system. It's not because I'm not interested in categories.
Please see (and comment on if you'd like) my informal investigation on "What's in Wikipedia?" at https://en.wikipedia.org/wiki/User:Smallbones/1000_random_results . If nothing else, you might be interested in the graphic https://commons.wikimedia.org/wiki/File:Size_of_English_Wikipedia_(1000_vol)...
Re: the gender gap, please take a look at the bottom of the write-up on how biographies (Women vs. Men) improve over time. It's got a new (AFAIK) use of the ORES output.
All comments welcome - here, on the discussion page, or, if you really want to lay into me, via e-mail.
Thanks, Pete User:Smallbones