I’d not worry about 6 year old learning English. He’ll learn in no time. Yes he’ll receive ESL services as every immigrant child has those available, but typically kids that young don’t need it for too long. And I’d not worry about Russian speaking teachers. It’s actually easier to become fluent in English without relying on a native language. She’ll eventually be able to work and will just have to adjust. I’d not worry about any of it. I’d only worry about father not giving permission. No I’d not move here without her child. I’d probably start a discussion with the father (if he is involved). Good luck