Is the Russian language widely spoken in most Eastern European countries?

Russian is only spoken widely in Russia and some territories that were part of USSR and had large Russian minority. You will not get anywhere in Central Europe with Russian. Generation that was forced to learn it is at least in their 40's and there was not much desire to learn a language of the occupiers. It will actually create immediately very hostile situation for you and endanger your personal safety. Central European nations do not even like when Americans tries to go there with Russian language. English is spoken by anyone under 40, especially at larger cities. Southern Slavs like Croats and Slovenians were never part of Soviet block, there is nobody who will speak or understand Russian. Western and Southern Slavic language are not mutually understandable and they will not understand Russian, which is Eastern Slavic.