Amazing survivors there, Jeff and I sure admire you for adopting these sad little orphans. Please keep us posted on their progress.
I'm with Ursula on not re-potting right now. Just clean out any dead material you can get to, and start watering and fertilizing those babies. A gentle spray with the hose might wash out any old, rotting medium to help clean things up a bit. Then as the weather gets more dry in the fall, you can add a handful or two of orchid bark to the baskets to hold a little bit more moisture around them. Go very dilute on the fertilizer at first, too - maybe 1/4 strength than what the package says. But you can fertilize every 5 days or so in the hot weather.
Vandas like to grow with their roots hanging out in the breeze like that, yes and without any medium whatsoever. But they do like to be sprayed with the hose until their roots turn green, every day pretty much, if it doesn't rain. Did I recall you said you have a mist system already in place at your house? Perfect for those orchids!
Have you watched the "Free video . . " at the top of the Orchids forum? It's really informative about growing orchids in Florida, a great reference and great advice from a true expert on the subject. (I have his books too, and they are great)