Should ezine sales be included in the query?

Probably not, but that depends on what the ezine is. If it's a respectable one that's fairly well known and respected, then sure. But if it's something that the agent probably wouldn't know, I wouldn't bother.

Either way, it probably wouldn't help you that much anyway--so don't worry too much.

One of the agent bloggers touched on this. The basic message was include magazine credits if they are major names (the New Yorker, Atlantic Monthly, Harper's) but not otherwise. I'll find the link and add it when I do.

ETA: Of course, now I can't find the blog post I was thinking of. I did find Nathan Bransford though, and he said to only include them if they are big names or directly pertinent to what you are querying.