..happens to be this little online game called Arcadia. You play four little mini-games all at once and it's really interesting to watch people play it. Some are stressed out from the very start, just by the THOUGHT of monitoring four separate events. To others it comes almost naturally. Also, it's interesting to see how long it takes before people begin to see which of the mini-games are important and which ones pretty much play themselves. The game: http://www.addictinggames.com/arcadia.html

The author of XKCD has an script that uploads a new cartoon at midnight every monday, wednesday and friday. Hence, if he goes on a long vacation, his site will run as normal.. But this also means that he needs a backlog of comics that are drawn, but not posted - which he has said himself that he has.

I have no official numbers, but i heard somewhere that he's several weeks ahead of the posting schedule, maybe months - so you should have done your searching long ago to get the same results as he did when researching.

If you read the mouseover-text of the comic it seems like he's pretty honest about the numbers, I don't see why he should make them up.