Short answers, pulled from the story.
Moses appointed seventy elders known as zekenim to share leadership, creating a body of seventy-one judges including himself. This odd number prevented voting deadlocks during decisions.
The assembly met every day within the Hall of Hewn Stones inside the Second Temple in Jerusalem except on festivals and the Sabbath day. Members included priests, Levites, and ordinary Jews with pure lineage allowing marriage to priests.
Yochanan ben Zakai negotiated with Roman Emperor Vespasian to re-establish the Sanhedrin at Yavneh after the destruction of the Second Temple in 70 CE. The seat moved to Usha under Gamaliel II in 80 CE, then shifted back to Yavneh in 116 before returning to Usha again.
Emperor Theodosius II outlawed the title of Nasi following the death of Gamaliel VI in 425, leading to an imperial decree in 429 that dissolved the ancient institution. Capital punishment was prescribed for any Rabbi who received ordination under earlier laws from 383 CE.
Napoleon Bonaparte convened a modern assembly known as the Grand Sanhedrin which did not follow traditional halakhic procedures used by ancient courts. Documents were written in Hebrew, French, German, and Italian to address all attendees while the Assembly of Notables invited delegates from European Jewish communities to meet on the 20th of October.