I have several Bulgarian e-mail friends of various ages. Until about 1990, the study of Russian was compulsory in all Bulgarian schools so most Bulgarians over about 40 speak it fluently. Now, some younger people speak Russian but almost all of them are fluent in English because this is a much more useful language.
the people who are over 35-40 studied russian at schools as a first foreign language but most of them didn't use it in their daily life because russian influence wasn't strong as such in Ukraine. But i think well-educated over 40 aged ones can help you.. Dobre doshli vav Bulgaria..
Russian tourists ususally get away without knowing Bulgarian because of the similarity of the language and they pick up Bulgarian quickly. Pronunciation is very easy for Russians. Bulgarians are also able to understand a lot of Russian, even if they never learned it but you can't rely on it. Bulgarian and Russian are close but there are also a lot of differences.
As Bulgarian like Russians are Christian Orthodox, written Russian borrowed a lot from Bulgarian as old-Slavic roots, which can't be said about Ukrainian or Belarusian (they borrowed more from Polish). A few examples of old Slavic roots borrowed from Bulgarian (there are also East Slavic roots for each of them): врата, враг, злато (злато-серебро), брада (брадобрей), град (Волгоград).
I never learned Bulgarian but if I open a Bulgarian text, it makes sense to me, I can understand quite a lot. It would be hard to follow the news on TV, maybe, although I would understand 30% to 70% but daily conversations would be quite easy to understand.
The reverse (Russian understood in Bulgaria) will be true because were more exposed to Russian than Russians to Bulgarian. They would have more trouble with the Russian grammar - complex case system is non-existent in Bulgarian (and Macedonian) but the have a notion of a definite article.
He says he will come here for business. Yes bulgarian and russian are very similar, i can also understand many russian words but! grammar is really different there are articles, perfect tense.. e.t.c.) so yes as a tourist it is very easy to understand but for business it doesn't seem like that..
Bulgarian, as lexical, is more similar to old-slavian than most of slavic languages
Don't forget St. Cyril and St. Methodius (look at cyrillic alphabet) pls ..