And a few tips
Old castle Vyšehrad (mostly outdoor walk, great views and historical architecture around)
Small river ferries are included in public transport ticket (currently only the city center ones)
Dům u Černé Matky Boží - Prague cubism exhibition (mostly applied design like architecture, furniture, so it is fun even for people who don't enjoy traditional paintings and so on).
If you do enjoy paintings, there are many choices depending on the era (13-14th century in old monastery, or 1918-1938 in a modern building).
To overlook the city, either Petrin (small Eiffel Tower - it is a copy, but 1890s copy) or towerpark - futuristic building with high rise restaurant and bar Oblaca (you can visit a viewing deck or book both view and restaurant deck).
Uber won a selection for the official airport taxi, and there is a convenient app-less process to order them at the airport kiosk for a regulated price, but if you do use an app, you can get a better price ordering from regular Uber drivers pool, not the airport -specific one. In that case the pickup is at departures, not arrivals level.