No, but communication plays a huge deal in being able to absorb the culture, as well as share your own.
Very true. Most places in the US are fairly welcoming if you can speak English and communicate. It's even common for xenophobes to cut out an exception for immigrants and minorities they know personally and feel friendly toward.
Also the american culture is very wide spread through media. Watching Hollywood, music, sitcoms, talk shows, stand ups etc. ever since I was 10 yo and able to understand english definitely helps absorbing the culture even from eastern Europe as myself. Visited the US for 2 weeks and really felt as if I was no stranger at all.
we don't care where you're from. I'm not running a little 'who's a citizen tally' in my head.