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."