Ookla: Yes, they had 80 copies on hand, fortunately. They had people calling them the day before, people who had read the article, worried that the store would sell out. It almost did!
Shrain: Elantris initial was between 11k and 12k. I've been told that's a tad above average. The second and third printings were between 1k and 2k each. I won't actually know about returns for some time yet. Ookla's numbers are a good judge, but they don't include a lot of markets, so it's tough to tell, even knowing the bookscan numbers. I'll have figures on returns sometime early next summer. (But, yes, 30% is the mark of an average book. Get more returns than that, and it's not a good sign. Get fewer than that, and it's a good sign.)
Oh, and the number they've been using for MISTBORN is 25k. They were talking 15k for ELANTRIS around this time, and did 11.5, if that gives you a frame of reference.
Vaj: Calmann-Lévy has the French rights. I honestly don't know what they'll do for the cover. Some of the smaller markets (Thai, for instance) have contacted Stephen and asked to use his cover. The larger markets, however, tend to like to do their own art. So, who knows what the French cover will look like. I wish I could tell you when it will be out, but I honestly don't know. Hopefully sometime next year.