hey flh, welcome to the forum.
You may find this recent thread helpful:
While your in Islamorada, stop into Sandy and Sue Moret's shop, Online Fly Shop - Florida Keys Outfitters - Fly Fishing School, Fly Rods, Fly Reels, Guided Fishing
at mile marker 81.2 (on the oceanside) to get the latest info.
You should also check out Robbies Marina Robbie's of Islamorada: Offering the widest diversity of recreational marine activities in Islamorada, Florida Keys - Offshore, Backcountry and Partyboat Fishing, Boat Rentals, Guided Tours, and Tarpon Feeding.
and feed the "pet" tarpon that are well over 100 pounds that school around the dock just to keep the fish gods happy before you cast a line for good kharma. It's truly an impressive sight. You can find them at mile marker 77.5 just after you go over the bridge on the bayside.
As far as the fishing, your best bet by far, is to get a guide, and if you go that route, it would be best to do it in advance as this will be peak Tarpon season. You can do so through Sandy and Sue's shop. The next best thing is to rent your own boat, and you can do that through Robbie's. You won't be able to rent a flats skiff, but you could get a small runabout/whaler type deal and fish channel edges, holes and edges for a variety of species (jacks, snappers, cuda, sharks etc, with an outside shot at tarpon/permit.
The DIY wading can be tough, and getting local conditions (tides etc, and suggestions from the shop and suggestions for local flats and their access points would be a very good idea to up your chances around Islamorada at places like Annes Beach etc). You might also consider a drive to Bahia Honda state park- It's a haul from Islamorada, but has extensive flats, and might be your best bet for bones if you are targeting them specifically, but you should have plenty of stuff to throw at if you're not picky.
Also be aware that if you're fishing on your own (without a guide) you will need a SW license, which can be picked up all over the place down there.
Have a great time, and let us all know how you do down there.
Good luck, bring plenty of sunscreen, a good hat, and polarized glasses.