Will my garmin work in Italy

If it is a model with Europe maps pre-loaded then yes. If not, it would need the Europe map micro sd card inserted.

Will our Garmin Nuvi with European maps work in Vienna to help us find our way walking around? I'm not sure about the confusing street addresses but we've used latitude and longitude from GoogleEarth on the Nuvi to find rural B&B's on previous trips to Europe.

The current maps from Garmin for Europe is 2013.10 (May 2012). Available on SD card for $70.00 from both Amazon and Garmin. SD cards cannot be updated. The DVD version (lifetime updates available for $$) available at Amazon for $83.00 and Garmin for $100.00, but you would also need to have a SD card inserted in your unit for the maps.