Answer:
Doing this with your job can be risky but doing it with smoking is always a good idea
Very helpful if you intend to go gently down a river.
Longer than a decade and shorter than a milennium
People want it, and when they have it, they use it by giving it
Deep, deep, do they go. Spreading out as they go. Never needing any air. They are sometimes as fine as hair
I met a man on the London bridge, he tipped his hat and drew his name, in this riddle I told you his name. What is it?