Tampa International Airport (TIA) is actually very easy to get around. Once you're off the plane you just follow the exit signs or follow the crowd as there is only one way to get from the airside to the terminal, which is via the very short troley. If you have checked baggages, you'll take the escalator down to the 1st floor at baggage claim and follow the signs to your airline flight #. I suggest that you look at TIA's website at: http://www.tampaairport.com/index.asp
for more info.
The beaches are about 30 miles from Tampa. If you're driving, you can take the Howard Frankland bridge to St. Pete beach, Treasure Island Beach or Madiera Beach. If you want to go to Clearwater beach, you'll need to take the Courtney Campbelll Causway via the Veteran's Expressway to Memorial Highway out of TIA.
The aquarium is opposite directions from the beaches. It's downtown Tampa near Chanelside. Whereas Busch Gardens is north of the airport. You'll need to drive onto I-275N and Exit Busch Blvd.
There are plenty of hotels and motels available, both on the beaches and in Tampa. Good luck to you. Hope you enjoy the area.