1) I don't understand "overall size rank". Based on the definitions, it is the "count of unique devices which visited the wiki during that month". What does this do with the size of the wiki?
Thank you very much for noticing this! It looks like we accidentally mixed up some of the definitions. I've restored the correct definition of overall size rank, which is "a composite ranking of wikis by monthly active editors and monthly unique devices (produced by taking the geometric mean of those two values)". I checked all of the other definitions and they should be correct.
2) I miss the size of the database (main namespace/content pages), which together with the number of content pages would give an impression of the mean size of the articles (I know this is not perfect, but better than nothing).
3) Many more wishes about additional metrics :D