1.I believe that old man should live with young people together.If there isn't any young people around him, he can't follow the step of the society.Of course young people have enough energy to help when he is in trouble.
2.I don't think so. In my opinion, old people should live with someone who is at the same age. They can have common ideas and talk together with pleasure.If with young people, they can't talk with them on the topic they like,because young people always think that they are not in the step of the modern sociey.