So, if my waitlist doesn't come through prior to 30-days before my arrival (or, is it departure?), do I need to call back to get on a 30-day waitlist, or are my chances exhausted at that point in time?
Yes, the waitlist is cleared at 31 days so you'll need to call back to be placed on the list again. At 7 days, the list is cleared again and you'd need to call daily.