Your presence is the best present so there are no expectations for gifts!
Passport, Sunscreen, swimsuits , several pairs of beach clothes and beach formal wear, hats, sunglasses, and anything else you bring on vacation. Make sure to bring beach appropriate shoes
You do not need to stay at the Hilton but that is where the discounted rooms are . There's many hotels and Airbnbs less than a few miles from the hotel should you wish to stay elsewhere.
Sunny most of the year! There is rarely bad weather in Aruba and temperatures range from mid 70s to mid 80s. The weather during the wedding will likely be in early 80s
Aruba is known for beach bars and seafood but has a variety of food for different palates. The hotel has 5 different restaurants with a few serving breakfast, but you are welcome to dine wherever you wish.