Luggage and bags:
Clothing/Shoes/Weather Gear: good walking shoes, water shoes(a real must, i could show you the scar from a shell that cut my foot :) light clothing (of course!;) a good hat.
Toiletries and Medical Supplies: bug spray for those real hot months!
Photo Equipment: i bring tons of film
Camping/Beach/Outdoor Gear: an umbrella on the beach is nice for shade,dont forget your fishing pole!
Miscellaneous: Coffee and lots of it! Who wants to waste tinme Sleeping here?!?!
You can expect a regular rain shower on a daily basis at certain times. It will usually be in the evening, though, so it shouldn't really ahve a big impact.
Photo Equipment: Lots of film!!! Zoom lenses (if you have) are extremely helpful when shooting at Ding Darling Wildlife Refuge. The birds, crocs and gators there are hard to miss.