Short answers, pulled from the story.
The Samaveda is a sacred Hindu text from around 1000 BCE that organizes hymns into musical meters and ritual aims. Embedded codes of swaras appear above or within the verses to indicate pitch direction.
Purandara Dasa lived between 1484 and 1564 in Hampi of the Vijayanagara Empire. He systematized classical Indian music theory and developed exercises called Suladi Sapta Tala.
Bruno Nettl states it is best conceptualized as unique array of melodic features mapped to aesthetic sentiment. The goal of a raga is to create rasa or mood atmosphere essence inner feeling through music.
Adi tala is the most widely used tala in South Indian system while teental dominates North Indian system. First count of any tala is called sam in both major systems of classical Indian music.
Ravi Shankar came to US in 1958 and started making albums that began 1960s penchant for Indian classical music there. He performed at Woodstock for audience over 500,000 in 1969 alongside Western rock blues soul acts.