No, I have not had to use the megaphone. We preflight ALL emergency equipment before the flight on each new plane we board. I was just thinking the purser probably looked hilarious running around with it, I know that is mean to say, but I would like to see it!!
About the perdiem, we are paid either the domestic or int'l. rate from check in to check out at the end of the trip. So the longer you are away the more $$ you get (and theoretically the more money you spend).