All you will need is an inexpensive international plug adaptor which you can buy at most airports. No one can predict what exchange rates will be. Banks do not all offer the same rate of exchange, but the bank at the airport usually has the best rate. Some, like the one in Montecastello, charge a flat commission for traveler's checks or cash. You can minimize the commission if a group exchanges money in one transaction.
Some people consider Italy expensive, but everyone's needs are different.
Bring at least as much as you would normally spend at home, and a little extra. Materials you're used to may be different or unavailable there. Bring your favorite materials if you're not sure. Expect to go through art supplies rapidly. Clay and plaster for normal class projects are covered by your tuition.