When listing faculty that I'm interested in, would it be a good idea to list faculty that are in a related department? I am currently applying to a M.S. Statistics program and have an easy first choice (whom I will refer to as "A") for someone with whom I would like to work. At this particular university I am applying to, the statistics and math departments are separate. A has worked with a professor in the math department ("B") on a subject that I am interested in. 

Would it be a good idea to list B on the list of faculty with whom I would be interested in working on my graduate school application?
I would also agree with sending the email to A. You could also email B to see his view. He may have already worked with MS Stat in the past, for example.

Because the two subjects aren't that too far apart, you may likely also be able to work out something that is tailored specifically to you. I haven't met too many professors who like to shoot everything down, so it never hurts to try.