Does a person sick with novel coronavirus need to spend hours in a small room with many other people to spread it? or could transmission happen from a short/quick contact like a handshake?

Transmission: Transmission seems to be from droplets, from a cough or sneeze. Or from getting virus particles on your hands, or on a surface, and having someone else touch the contaminated object. If you are positive for Covid-19 you can infect 1 person by shedding virus in their presence, or a room full of people by being in close proximity. Call your General Physician for testing and instructions.