No, you can only use reef safe sunscreen. If you travel with non-reef safe, it will be confiscated. If you are checking a bag, it’s best to bring your own reef safe sunscreen as it will be more affordable to purchase from the states (on island, the cheapest goes for around $18 but it is money well spent!).
No, a passport is unnecessary but may save time at the airport. It is also suggested that you and your party plan to use the same type of ID as there are 2 separate lines for customs at the airport (ID or passport).
Virtually every beach can be snorkeled at so if you enjoy it, we would say it’s totally worth the suitcase room! There are companies that will rent gear for the day/week so it is something to also look into!