YES! It is STRONGLY recommended that you buy alcohol on landing at the duty free (yes, we understand that duty free is usually bought when you're LEAVING a country, but this is not the case in Trinidad, and you can get EXCELLENT prices once you land that will not be available during your stay)
Download the TTrideshare app before you touch down (internet in the airport is touch and go)-- it's the equivalent of Uber/Lyft on island (neither of those exist in Trinidad currently). Renting a car is a great option, though remember it's left lane driving, like the UK, and there is NO turning left on a red light after stopping.
While many vendors are glad to take USD, many places won't be able to (or will give you a shit exchange rate)-- best to get some TTD (Trinidad and Tobago Dollars) at the airport ATM.
Avoid flashing cash and jewelry, and be mindful of your surroundings. Don't take rides from strangers-- please download TTrideshare (the equivalent of Uber/Lyft in the US/Canada) before you leave. You can also use TTrideshare coming out of the airport.
Street food is life in Trinidad, so the emphasis is not on upscale restaurants; that being said, House of Chan (Chinese), Buzo (Italian), Salt and Pepper (Indian), Roti Cafe (curry), IrieBites (jerk everything), and Pappy's (spicy fried chicken) are all solid choices. Also.... KFC is different on island, and it. Is. Delicious. Get some 'spicy' chicken and thank us later.
There are flights from Trinidad to Tobago every hour or so (about 25 min each way and $50USD round trip), and there are multiple ferries leaving each day (about 4 hours each way and $20USD round trip). While you CAN fly standby, it's HIGHLY recommened that you book ahead if you're interested in a day+ trip. Also, it's GORGEOUS (some of the best beaches in the world) and highly recommended that you go if you have time.