I can't imagine how people relocate if they don't know English at all. I believe most of people who is going to relocate know English at least on basic level.
No, not necessarily. You'll pick up English in no time, if you have enough desire, courage and attitude.
I didn't. Even despite that I have been studying English at school and at college, I knew as little, as to not understand the simple phrase "What is your name?". My wife didn't know either. She's been studying German all her life. Well, she works as a teacher in public school now, and English is her main tool at work. :)