Mission # 1: To get a Russian student visa in Belgium

Problems: I had to wait 3 months to get the invitation from Novosibirsk State University. I left on my trip before that, and it`s impossible to get a visa in another EU country if you`re not a resident (it may be possible in one of the Baltic states, but that may not be the case for student visas, and anyway I didn`t want to take any risk), so I had to return to Belgium.
There are enormous lines for the Russian consulate in Antwerp that barely move, so I had to return 3 times before I got in. That 3rd time I got there at 8, there were 3 people before me, they are open 10-12.30, I got in just after 12.
Result: Success. 2 months in Russia.

Mission # 2: To get a Russian tourist visa in Mongolia
Problems: First, they wouldn`t accept my perfectly valid insurance, so I had to go to Aeroflot to buy new insurance I would never use. Apparantly they do this to most Europeans.
Then, they wanted me to have a train ticket out of St.Petersburg, as that was the last stop on the itinerary on my invitation. They claimed I could get it at the train station in UB, but they only sell tickets out of Moscow. I could`ve bought a plane ticket out of St. Petersburg and cancelled it after I got the visa, but I`m sure they would`ve just come up with something else.
Result: Failure. 9 extra days in Mongolia, fly back to Berlin.