Once you have confirmed your travel (literally show them you booked a flight and room) they will confirm the location you want. It doesn't matter how small your party is, but your party can be too big for certain locations. Obviously, you also need to purchase the particular wedding packages that include a beach reception
I always had so many questions but I learned to only ask one question per email. Otherwise they skip over things. My advice, write an email with this question only and see what you get back.