Regarding the space thing, absolutely true. While everyone has their 'bubble', Americans tend to have much larger ones. If you can't get used to people being in your space, then God help you if you ever ride on a Russian metro or bus.
Both are usually fairly packed. One thing I recall from riding on the автобусы was the procedure for getting on and then getting off. Getting on was basically everyone cramming onto the overfull bus, and as soon as I everyone was on the bus driver would leave. People might pay as they're boarding, but usually many people, especially in the back, don't get to pay their fare until after the bus is already moving. In America you usually have to have exact change to ride the bus, and the bus doesn't leave until everyone has paid; my experience over there was people will pass money up to the driver, who will then make change and pass it back. It seemed like a very honesty-based system--people never seemed to try and "cheat" and not pay at all, and all of your change would make it back to you despite passing through the hands of half a dozen strangers. The drivers making change was a little bit disconcerting to me at first, but I never saw an accident. Don't be surprised if you go and your bus driver looks like this:



For getting off the process seemed to consist of tapping the person in front of you (usually after the bus leaves the stop before yours and is still in motion) and asking them вы выходите? If the answer was no, you would begin this 'dance' of trading places (keep in mind the bus is usually extremely packed). You would continue to do this until the person ahead of you is responds that they are getting off, and then you are to assume that they have done the same thing you just did and that everyone in front of them is getting off as well.

This might seem like normal every day activity for a native, but keep in mind that most Americans have their own cars and transport themselves (except for in the very big cities).

I don't know if this holds true for everywhere, but I noticed over the course of the month I spent over there (these observations are for Kiev, Ukraine by the way, although as the 'mother of all Russian cities' I imagine most of it holds true for many parts of Russia) that many people would re-wear the same clothes a lot. In America it's usually considered bad hygiene to not shower at least once a day and to wear the same pair of clothes twice without washing them (though you can get away with re-wearing a pair of джинсы).

Also, I don't know if this was just the family I was living with, but most Americans have access to a washer and dryer. The family I lived with in Kiev had a very small washing machine in the bathroom and then...I don't know exactly what to call it because I've never seen one before, but the best way I could describe it was they had something that looked like like multiple towel racks that radiated heat that they would hang their clothes on to dry.

In America sales people are very courteous and will nearly bend over backwards to help you. Over there, don't be surprised if the shopkeeper is quite literally yelling at you to see what you want within ten seconds of walking in the door. (This, of course, varies on the store. I went to a bookstore and the people there were fairly kind and helpful) Also over there while standing in line at a restaurant or street vendor it'd be a good idea to know what you want well before it's time for you to order. In America people can quite often hold the line trying to decide what they want to buy.

Don't try to leave your change. In America many establishments have "take-a-penny" cups by the register. The idea is if you get a few pennies as change you can leave it for someone else to use to make things come out even. (For example, if your change is 1 cent you can leave it in the cup. Then perhaps the next person, or someone else later, who has a total of $1.01 can give the person at the register $1 and then a penny from the cup. That way they don't have to give the person at the register $2 and receive $0.99 cents in change--a lot of coins are annoying to carry around.) While in Kiev I tried to leave my change with a lady selling newspapers, but she was quite adamant about making me take it.