What Rusty said. Those are hooks they use to pull the bus back out of a lake or something. You should find them on both ends of your bus.
The class 5 hitch is an excellent choice. It fits the bus frame and it's solid. Adjustible hitches will work if you're towing very light trailers, but someone always overloads the hitch. Get a good one and you don't need to wonder if it will do the job.