Thucy, I live near a university, in the outskirts of Stockholm. The surrounding area has tons of blocks of flats. Some are dedicated to students, the rest are just cheap flats, mostly built in the 60s and 70s to house a growing population cheaply. It's not luxurious in any way but it's no ghetto neither, it's just cheap living, which suits students and recent refugees well. I hear a lot of languages. Arabic, Persian, Somali, Serbo-Croatian, Vietnamese, Korean, etc. etc. Stockholm has some problems with segregation, but it's not along ethnic lines, it's primarily along socio-economic lines. Wealthy people are clustered in the centre or in suburbs with houses, while recent immigrants, students and working class people live in the cheaper areas with blocks of flats.
For inter-ethnic communication, either Swedish or English works, but we tend to default more to English, especially students. Most university courses I've taken in Stockholm have actually been in English. It's rare to have literature in Swedish. And why bother? With our liberal immigration policy and tons of exchange students, and with good English education in our public schools, good literature and experienced international teachers can be integrated seamlessly, making it easier to cooperate with universities and research in other countries. I'd say that my English is better than most Swedes since I've lived in Ireland for a while, but the general level of English is not far from mine.