Short answers, pulled from the story.
The stadion was a short sprint of roughly 200 yards held at the Ancient Olympic Games and other Panhellenic Games. It was the premier event of the gymnikos agon, the nude athletic competition, and the most prestigious running event in the ancient Greek world. The winner was often regarded as the overall champion of the entire Games.
Coroebus of Elis won the first recorded stadion at the Ancient Olympic Games in 776 BC. As the inaugural champion, he gave his name to the first Olympiad, following a tradition in which each four-year Olympiad was named after that cycle's stadion victor.
From 776 to 724 BC, the stadion was the sole event at the Olympic Games. During that period of more than fifty years, winning the stadion sprint was the only way to become an Olympic champion.
The Greek word stadion referred to both the race and the facility where it was held. Latin borrowed the word as stadium, which passed into English as the modern word stadium. The race also gave its name to a unit of length in ancient measurement systems.
The balbis was a stone starting line used in the stadion race, in place by the fifth century BC. It was refined over time to include double grooves spaced 10-12 cm apart, into which runners placed their toes to gain leverage at the start.
Stadion runners started from a standing position, with their arms likely stretched out in front of them, rather than crouching as modern sprinters do. A trumpet blow signaled the start, and officials called the agonothetai monitored the line to prevent false starts.