If you are from North America or North/Western Europe you will probably find Zadar a very cheap tourist destination.
You can get decent 3 star hotels for €25-55 (low season) or €50-110 (high season). Even five star hotels in Zadar cost from €75-110 (low season) or €110-250 (high season).
(Most people get better deals with private apartments, rather than hotels though!)
Eating out is very cheap too. A pizza might cost €5, and beers at around €1.75-2.
You will probably have no problem exchanging money in Zadar, but we recommend you only exchange at banks. You will generally need to provide some form of identification (passport, or often a drivers license is enough).
It is easy to find banks in Zadar.