Forces of Nature!

Today's discussion at the lunch table was about a number of things actually, one of them being the g-forces people can take.
here are some questions:
1. Who was the first person to experiment with G-Forces?
2. What is the max that we humans can take?
3. What are the g-forces experienced by different people in professions such as formula-1, astronauts, fighter pilots etc?
4. On a roller-coaster?