First of all... breathe......
There are tons of car rental agencies out there and honestly they are all fine. My first car rental was through a package deal and I had to go with what they offered me.
Alamo was off site and we did just fine.
Mousesavers.com has some very good info about discounts specific to Florida. Do some reading on the rental car pages and soak in what Mary has there.
Personally, I like National and their Emerald Aisle service. You can read more about it at Mousesavers. I will rent from whoever has the cheapest rates, and for my March trip that is currently
Budget. I am hoping National or Alamo come down, but will make it work.
As far as insurance, you don't need insurance if your home car insurance policy covers a rental car. Many credit cards also offer rental insurance. I have never purchased the insurance as I already have coverage.
Take your time and do enter as many codes as you can to find the best rates. Over the years I have found the best ones that work for me and I always enter those codes. If you have an Entertainment book, they have some nice coupons and codes. I also always find a good rate with National using the Continental Code of 5007160. You have to be a frequent flier member, but it is free. Costcotravel.com also has some nice discounts if you are a member....
Best of luck.....
Duds