Originally called the Brodie helmet, known in the US as the "Tommy Helmet", and adapted by the US and produced in the US up until the M1 replaced it in 1942, and known as the M-1917 helmet (because it was a WWI helmet).
They are the same. "Brody Helmet" is the name it is known by in the UK. In the US it is the M1917.
About $30,000 year if you work for a Major Airline.
a fary poops in it
This depends on what type of helmet it is and what country you are in. In Canada we respect the US specification but have our own system
No.
how many hours flight from us to Malaysia
Yes. Most of US states, require a rider to wear a helmet.
They all should have.
Yes
A flight from the US to the UK takes about 9 hours.
Only if you return by land; if you take a flight you must have your passport with you.