Only tourists, and no, it's not customary to talk to strangers in my city. Several years ago, in an English class, a classmate told a story about him approaching a group of foreign guys to be friendly and practice his English, and these guys thought he was a pimp. Lol.
I live in Glasgow and see hundreds of tourists and foreign students every day. Glaswegians are very friendly but unlikely to start a conversation but always willing to help if someone gets lost.
I live in Canada where anybody could be foreigner. It's hard to tell.
Yes, there are a lot of immigrants where I live. And at my school, there are also a lot of foreign students as well. I don't usually approach random strangers and talk to them, but if I have a reason for interacting with somebody, then yes I will talk to them.