A couple of links that you may find helpful.
How to Become a Florida Resident: 12 Steps (with Pictures)
Moving to Florida
Drivers license and car registration (including new FL title that will be needed) can be easily and quickly completed here. Not particularly cheap though. They are even friendly and helpful. Nothing like the MA Registry of Motor Vehicles.
Randy Mask - Sumter County Tax Collector
(The building with the gold dome next to Pinellas Plaza) There are also other places to accomplish this nearby.