Doctor Q runs it in his spare time! I guess those Stats are not 100% accurate, but yes it is interesting. I find it hard to keep up with everything hear on MR, so just as well I'm not on all these other sites they list.
Probably from various sources. The page itself isn't dynamic -- the picture count is statically defined and the counters are just Javascript, running locally, so the numbers aren't really real.
Also, the site is incorrect stating the Internet is less than 30 years old. I was using it in 1980, and it wasn't new then.