The I4 construction has been going on for years and will continue indefinitely! It will be several more years, at least.
I4 is really bad in the lakeland area, about halfway to WDW. There are narrow lanes with Jersey barriers and sudden, severe lane shifts with little or no warning. The last time we drove through there a couple of weeks ago, there was a caravan ON TOP of the barriers!! The nutcases who drive in Florida do not slow down through these areas, and don't look when they change lanes. A previous poster said it's nothing like the Boston traffic. I've done both, and right now, that Lakeland stretch is pretty bad. Boston drivers are fast and rude (cutting people off, not letting you go, etc) but predictable. Florida drivers are just plain dumb sometimes. SORRY!
They have opened new lanes from exits 38 to exit 58 (your first WDE exit on I4 from Tampa is exit 62). So, it is a little bit better lately. It will definitely take you closer to 90 minutes and time of day is not always a factor... construction really slows things down after 9pm. WDW to Naples will take you 3 hours to the minute. We do the drive somewhat regularly.
We haven't used the Tampa airport in a couple of years, but it is smaller than Orlando, but same set up. You have to take the "monorail" from the terminal to the main airport building, and then an escalator to baggage claim. If I remember correctly, the baggage claim and rental cars are on the same level. Someone else will have to tell you for sure.
I think you'll do enjoy flying into Tampa, especially because you're also going to Naples. Just PLEASE be careful on I4 though Lakeland.... Exits 27-38.