We are travelling to Graz via Vienna airport this week and need to know how to get to the correct station (Südbahnhof?) to catch the train to Graz, the frequency of trains, whether these are direct or involve a change, and the approx. cost. Is it cheaper to book in advance or on arrival. Haven't been to Graz in 20 years so don't want to rely on my memory of transport connections from back then. Thanks in advance for any help you can give.