the little part that lies between poland and lithuania, where kaliningrad is the capital off.
Do they speak primarily russian or lithuanian or polish?

Can I get around Eastern Europe if I only speak Russian?
Here are some of the countries in Eastern Europe: Poland, Lithuania, Belarus, Czech Republic, Slovakia, Hungary, Romania, Ukraine, Moldova, Bulgaria, Serbia, Bosnia, and Croatia.

Which countries have a large population of Russian speakers, and which countries do not?

My dad is from Poland and I want to learn a language that would help me in learning Polish from him.
Would Russian be helpful because they are both Slavic languages?

I'm an American, and I took Russian for a while in college, but no Polish.
Since Poland was Communist for many years, and also because it's another Slavic languages, will most Poles be able to speak and understand Russian, too?