Hello Scarlett
You will enjoy Cuba,some of the most beautiful people to meet.
We stopped in the Cayo Santa Maria hotel,the staff there were great,when we went there was in the month of May, I would not go again in this month because we were bit to death with mozzies, there is a lot of greenery around the hotel complex.
You go over a causeway ( road ) that was built to get to the cayos,has trips we went on different ones,but for a child I couldn't say.
Take with you old make up etc, razors,colouring books & crayons,any old clothes you have spare.
They have nothing so would welcome anything,but watch the weight with your luggage going out,if you do take extras.
There was one of the waitresses getting married,got nothing,my wife gave her a white dress,someone else with us gave her a pair white shoes & bag.
Then we put some money in a wallet as a present,she was in tears.
You should be okay in september,we went to Quadalavaca near Holguin in this month.
The beaches are beautiful. Enjoy
The currency is a closed currency,the exchange rates were the same at the airport & hotels in Cuba.
The head waiter in the beach bar is a great little guy.