No extended service plan / extended warranty is going to be sold that on average pays out more than the buyer pays in; that, after all, would simply put the company selling it into bankruptcy eventually. I'd forego them as a general rule--and doubly so if you would have to get the RV from Rhode Island back to Florida for any service to make use of them.
As far as things to get for outfitting, you probably don't need to go overboard initially. Bedding, basic consumables (TP, paper towels, soap, etc.), a water and sewer hose and sewer elbow, cleaning supplies and tools, trash can and trash bags, lighter for the stove/oven...those sorts of essentials. If you forget something, it is of course entirely possible to purchase it along the way.
For tools, I would get a halfway decent #2 square screwdriver, an adjustable wrench, and a pair of pliers, and go from there. Having all the stuff needed to put on the spare tire--if you have a spare--is also a good idea: a suitable jack, wheel chocks, and a wrench of some sort with sufficient leverage to manipulate the lug nuts. Warning triangles and/or flares are also a very good idea.
I do find I make very good use of a windshield cleaning squeegee.
