In normal conversation, I can't think of a way of just asking a person how much he or she weighs - at least in the West. A man might think it strange. You could ask it of a woman, if you didn't care whether you spoke to her ever again. There would have to good reason (doctor, skydiving, etc.) to ask such a question. The question would be "What is your weight, approximately." [If asking a woman, start running - now] Room: "What's the area of this room?" Wishing someone a long life. "Have a good life." There are other phrases - used mostly in situations where the person is close to you. "Good luck" is used, but almost always when a person might face bad luck. Usually, Westerners think in shorter time periods - "Have a good time", "Have a good trip."

As Maxey said, it is impolite in western culture to ask people about their weight, although it may be quite acceptable in your culture. You can say, What size is this room or How big is this room? You can say, I wish you all the best in life.