By train and bus
There are train services from many European cities; you can look up timetable on the excellent Die Bahn website.
There are international bus services from Austria (Graz & Wien), Czech Republic (Brno & Prague), Italy (Trieste), Germany (various including Dortmund, Dusseldorf, Frankfurt, Hamburg, Munich, Stuttgart), and Switzerland (Lucerne & Zurich). Routes operated by Croatia Bus.
By car you can reach Zagreb by motorway from Ljubljana or Budapest.
The unit of currency in Croatia is the Kuna ( 1kuna = aprox.7.3 Euro). Foreign currency can easily be exchanged at the airport or at exchange bureaus.
All major credit cards are accepted, including VISA, MasterCard, American Express, Diners.
EU nationals do not require a visa to enter the Republic of Croatia. Generally speaking, all other foreigners require a visa for stays in Croatia. A visa is not required for semi-annual visits of up to three months for nationals of those countries for which the European Community has abolished the visa requirement. For details see: http://www.mvpei.hr/MVP.asp?pcpid=1615