The new site does seem to have more entries, but I haven't checked what the differences are exactly (e.g. are some things counted in one but not in other). For example the table shows 36 movies from 1910s, in AniDB there is only 26 (search with start time between 1.1.1910 and 1.1.1920, the only entries are movies).
Likely. Do you have "hide synonyms" on or off? With it on I saw 2301 pages of results (last item being #69055), with it off the number I found 12479 entries. Not sure what that ~1400 difference compared to stats is though.
There's something not obvious because it requires login... it has entries for several files for each episode.
The files are fansubs/rips/etc. Each file has hashes and information about container and the streams in it (codec, resolution, bitrate for video, also the language for audio and subs). Also whether the ep is censored if applicable, whether it's a dvdrip/bdrip/streamrip... a ton of information.
Their statistics in homepage doesn’t claim they are bigger than Anime Taizen. They said they only have 13898 animes (title?).
And then they mentioned that it is not only for Japan anime but China and Korea as well.
anidb is a (truly wonderful) monster.