It does not necessarily have to be a previous IOTW
Absolutely not, in fact this is normally discouraged. Also wouldn't be fair to new members, or members who haven't had a IOTW previously. So I'm guessing this comp includes any image in the gallery, (previous winner or not)
So basically anyone who has a image in the gallery will have a chance to win.
Probaly not the right place, but several times I have had the following error message when changing pages, or when I wanted to use the spell checker.
Internal Server Error
Thanks for the heads up. Hopefully just a server glitch. I'll check it out though.