The US does require it to be mailed in as per the Embassy website and personal experience. Quite a few steps involved, I did a full write up of each step in a Chiang Mai group.
As James mentioned, India now gets 60 day visa exempt entry. Sounds like your colleagues have old info or tried entering before the new rule came into effect.
For the op's info, CM immigration has been pretty empty so may be quick to get your answers from them. Also, there are two assistants just before going in that checks all the paper work and may be able to assist you.