Florida doesn't differentiate between "resident" and "non-resident" CWFL's (the technical term for our LTC, although most call it a CWP). You can apply through the mail, and if you move you just change your address on it. Some states that FL has reciprocity with require one to be a resident of Florida, but that's only a small handful of them anyway. The big advantage of the CWP is that you avoid the waiting periods, which are different in every county, and include things such as transfers. Some FFL's will also err on the side of caution when it comes to waiting periods to and make you wait when you technically don't have to, but again, the CWP will bypass all of that. It also opens up a lot of doors for vehicle carry and similar things, especially for those who live in condos/apartments. But you don't need anything other than a valid photo ID to buy a gun in Florida, and there's no paperwork requirement or waiting period for private sales. In fact, it appears that it's illegal to keep a bill of sale in a FTF transaction in FL, but that's a separate topic.
Something for you to keep in mind though, ATF is very aggressive in their enforcement of federal law down here. I'm not suggesting that you'd be breaking the law, but if I were you I'd CYA as far as dual residency goes to prevent any misunderstandings on their part. They have a big presence, much greater than I ever saw in Mass., and some FFL's live in fear of them, so they may not want to sell to you. Some won't even sell long guns to residents of other states, even though it's legal.
The Division of Licensing is tricky in some areas, so you might actually get the CWP faster through the mail than you could by scheduling an appointment to go in in person, but it's a simple process, and it's recognized in 2/3's of the US for FL residents.
I'm on the ball with the FL procedures, so ask away if you have any questions about that, but federal dual residency law is not my area of expertise. Like I said, be able to show that you're legal, and avoid anything where there might be gray area, but some others should be able to give you more info on that area in particular.