It's a bit tricky to visit Russia without staying in a hostel/hotel; I'm assuming you will be crashing at your friends place. In order to get a visa you need a "hotel invitation", and once in Russia the hotel has to file all kinds of paper work to "register" your presence in the country with the government. Without this registration you may not be permitted to leave without paying large fines or worse.
The most direct way to get a visa is to visit the Russian Embassy in Vienna:
http://vienna.rusembassy.org/rusvisa.html
But the paper work is tricky and one small mistake will result in a rejected application. In Vienna I would track down a travel agent that specializes in Russian travel and let them do the paper work. You should also head over to the http://www.Tripadvisor.com Russia forums. There are lots of locals that frequent the site that can give you more insight.