Kona Airport is similar to other Hawaii airports. KOA Airport is open air. The buildings aere open to the air. You can see through to the gates and baggage claim. Open terminal building design works in Hawaii.
The terminal map below will help orient you to the locations in the airport. Note their are 2 terminals, multiple gates, baggage claim, food and souvenirs.
There are no car rentals at the terminal. Shuttles take you to the rental car locations.