Hoya first of all clearing customs and getting into town should be about 30 minutes or so by taxi or bus. So you will have lots of time. It is best to use an ATM at the airport or in town to get Swiss Francs. But you can also change cash at the airport. I find wandering the halls at the UN is quite interesting. Try lunch in one of the main cafeterias there. However off and on they limit access to the public. It is worth a try. Then go up to the old town and check out one of the Cathedrals that has a very ancient burial chamber in the basement. It's pretty interesting.

Buses and taxis are plentiful so it is easy to get around.