Your last point is good and applies to more than Russians (though it accurately describes my experience with Russians too). I've noticed it to a lesser extent (everything is to a lesser extent compared with Russians) in East coast vs. West coast Americans. In California people are friendlier on the surface but harder to really get to know. In New York the surfaces are ruder but once you're accepted as not a stranger the interactions are warmer and more satisfying.

Somewhat related, the late cartoonist Callahan had a classic called "The Difference Between New York and LA". In one panel, labeled LA, was a guy saying "Have a nice day" and thinking "Fuck you." In the opposite panel, labeled New York, was a guy saying "Fuck you" and thinking "Have a nice day".