Nelson's Dockyard and Stingray City

Wondering about how long it takes to get from pier to the Dockyard, what would be the best way to go for 6 people and the approx. cost to do so. Also, how much time on average is needed to the best spots.

We are also looking at the possibility of Stingray City and wondering what the best way to get there would be and what the transportation would cost approx. Do you know if it is a set time that you need for that or do you come and go as you wish

Unfortunately, we have only the one day on island