I don't have complete information (see below), but here's our experience (so far):
We are switching to Florida (Polk county) from Texas (Polk county via Escapees). We have a 2012 Ford Escape, 2016 F350 and 2015 Big Country. The Escape is paid for, the other two have loans against them. The only information I didn't know before we went in was that they need the title sent from the lienholders before you can register your vehicles, so the F350 and RV are still with Texas tags for a little longer.
The title fee, as mentioned earlier in the thread, is around $100. That will apply to each vehicle. I don't have the breakdown in front of me, but the total registration cost (aside from the title fee) on the Escape was $319. $28 of that was because we got a specialty plate, $225 of that was a one-time initial registration fee. I'm not clear if that is per vehicle or per person. Note that registrations expire on your birthday. Mine is in 6 months.
You have the choice of having the local tax office hold a physical paper title, having them hold an electronic title or having them send you a physical printed title (if the vehicle does not have a lienholder). Note that if you have your title in hand and lose it, you'll have to pay around $85 to have another issued. I suspect if they lost their physical copy, they would just print another if you needed it.
They require a form to be filled out verifying your VIN number and mileage for any vehicle with a motor, so the RV is exempt from that requirement. We took the car and truck to the local Ford dealer and they filled them out for free. Having a dealer do it avoids having to have them notarized.
If you purchased any of your vehicles in the last 6 months, you will be on the hook for any difference in sales tax from the state you are moving from to Florida. We bought the Escape less than 6 months ago and owed the difference in Florida taxes vs. Texas taxes. Fortunately, that was only $10.
I'll give an update when we get the truck and RV registered, but that won't be until we get back down here in April.
Per insurance costs, we found that ours were much lower as compared to our rates in Texas. The truck and car rates (combined) dropped about $500 every six months. Our trailer insurance (full-timers) dropped around $500 for the year (admittedly, part of that was due to switching from replacement value coverage to declared value coverage, which is cheaper).