Do I need to apply for a 24hour transit or 72 hour transit? If so, where do I get an application?

Barbara, you are qualified for both. I think you can make use of 24 hours free transit. When you arrive, please require the stay permit at the immigration. It's a stamp like 72 hours free transit. The difference is that you have short time stay. With this stay permit, you can exit the airport to stay and do sightseeing.