@smileyface - though Admissions suggested waiting 3 days before emailing a new ambassador, after getting a delayed response, I just went ahead and e-mailed everyone at once. It turned out that I only got 1 response. But worse comes to worse, if multiple people offer to interview you, you can respectfully decline some of the ambassadors.
@pacifictoatlantic - admissions provides you with a database to search which provides you with the information of 9 ambassadors (the max amount of people you can contact to interview.) if you are so lucky that the search returns one of your friends, well... Let's just say that if we both end up going to CBS, I'd like to make sure we hang out! :D but anyway, my point is that the interview ambassador selection is fairly random.