Take them before you start your masters program, you don't want to worry about them on top of your COMD classes. Honestly, I did most of mine online and basically went on quizlet for the answers. (Except for stats, I took that in undergrad).
I don't know the number of people on the waitlist, but congrats on the waitlist though! They seemed like a good program from my interview with them! They had a lot of interviews and I'm sure they declined admissions / waitlists to many people. Feel great that you made it this far!
My friend that got waitlisted said that he was near the "top" of the waitlist. I think that's just a generic email though.. I don't think they would tell someone that they were near the bottom of the waitlist..