They have open air buses that go every few mins from port and it's something like $20 RT.. You just hop on the next one when returning(20mins trip). There is an entrance fee but it's nominal like $4 to the government. You can get a chair for $5 or bring a towel they have picnic tables to sit at if you get there early and grab one.
It's very safe and I would guess it's all run by one company or the government. Food and drinks in the one bar isn't cheap you might want to plan on going to lunch when in town after returning. If you want to drink a lot and want to save money bring a six pack from the many local liquor stores or a liter of bargain vodka for $4 liter.
Beautiful beach and decent snorkeling. Variety of fish was small but quantity is huge plus they have a few turtles and many sting rays if you go farther away from the crowds.
Don't forget the sunblock!