June is a great time to go to Vienna (Wien in German). You should have absolutly no problems with getting around, the tourist infrastructure is very developed, many people speak excellent English (although any attempt to learn German is always appriciated) and is overall a nice place. To avoid offence, always greet shop owners, especially outside of Vienna with 'Gruess Gott' and say 'Auf Wiedersehen' when leaving. It is a really small thing that goes really far. The only places I have been in Austria where not speaking any German would be a problem are small villages, where although they understand my Berlin-accented German, I often have no idea what they are saying to me. The U-Bahn (Subway), S-Bahn (suburban light-rail) and Tram systems of Vienna are easy to use, and the ticket machines have directions in English. Off the record, you really don't have to buy a ticket, my girlfriend lived in Vienna for six months, rode the tram every day, and was never checked. But if you are caught, it is 40 EUR fine on the spot.

If you are flying into VIE, take the S-Bahn into the city, not the CAT. Although the CAT is a little faster, it costs three times the price of an S-Bahn ticket (on the route to the airport, your ticket will most definatly be checked). Spend the Euros you save on a good Viennese coffeehouse.