1. 他从五岁就开始拉小提琴了 is right.1.My manual says: 他从五岁就开始拉小提琴了. Can that be right?
2.Is it possible just to say: 他从五岁（or 从五岁的时候）拉了小提琴了?
What does 开始 do here? It`s not 'When did he start playing',isn`t it,that we have to translate?
I just thought it would be as in: 他在上海住了两年了 - He`s been living in Shanghai for two years
3.How would you translate 'He`s been living in Shanghai since he was 5'?