You already have your answer about the license... although, I am curious why you would want another license (from FL). A second license won't make you a better operator.
Considering your costs...
I rented a 23' center console at Pennekamp State Park and went out for a half day. We hit several reefs at our own pace, with noone around. It was great! We dove and snorkelled in groups of 3, always leaving someone on the boat. We were all capable of operating the boat.
I found that with 4 divers aboard, we came out even financially, compared to getting on a cattle boat. The cost of the boat rental and fuel compared to 4 two tank trips is about the same. With the added freedom... it was a winner!
Consider how far you will have to motor to your bugs before you decide on the rental location.
Good luck!
p.s. If you decide to rent... don't rely on the photocopied charts they give you. Bring at least a handheld gps.