I don't know about Prague and Budapest but I was in Vienna last year and discovered that:-
1. Debit and credit cards are not accepted as freely as they are in the UK. Most small shops, cafes, konditorie and ice cream parlours do not take them. Many restaurants do not take them either. If they do there is usually a Visa or Mastercard sign, which can be small and hard to see.
2. If you have a pre-loaded euro cash card banks have a minimum of 100 euros as withdrawal, but ATM's have no minimum. Some ATMs will display language options for withdrawals.
3. There are cycle lanes, designated by parallel blue lines on some pavements in the city centre.
4. Don't let any of this out you off. Vienna is the most beautiful and civilised city imaginable. You will love it.
Sylvia