Short answers, pulled from the story.
Herman Potočnik wrote the book in 1929 that predicted humanity would place stations in the sky that never moved. He described the precise mechanics of what we now call geosynchronous orbits and outlined how a satellite could match Earth's rotation to hover over a single point.
Arthur C. Clarke published his paper titled Extra-Terrestrial Relays in Wireless World magazine in 1945. The paper laid out the mathematical and practical foundations for what is now known as the Clarke Belt and proposed that three satellites spaced evenly around the equator could provide global radio coverage.
Syncom 2 successfully relayed television transmissions on the 23rd of August 1963. This event marked the first time a geosynchronous satellite had enabled international communication from a moving vessel when US President John F. Kennedy phoned Nigerian prime minister Abubakar Tafawa Balewa from a ship.
A geosynchronous orbit requires a specific altitude of approximately 35,786 kilometers above mean sea level. At this distance, the satellite's orbital period must be exactly 23 hours, 56 minutes, and 4 seconds to match the Earth's sidereal day.
When geosynchronous satellites run out of thruster fuel, they are moved into a higher graveyard orbit. It is not feasible to deorbit these satellites because doing so would take far more fuel than is used by slightly elevating the orbit to ensure a 90% chance of moving over 200 kilometers above the geostationary belt.