Short answers, pulled from the story.
The Chandogya Upanishad is a Sanskrit text embedded in the Chandogya Brahmana of the Sama Veda of Hinduism. It belongs to the Tandya school of the Samaveda and is listed as the ninth Upanishad in the Muktika canon of 108 Upanishads.
Scholars estimate the Chandogya Upanishad was composed between 800 BCE and 600 BCE, placing it before the rise of Buddhism. A 1998 review by Patrick Olivelle dates it to the 7th or 6th century BCE, give or take a century, while Stephen Phillips argues it was completed in the early part of the 8th century BCE.
Tat Tvam Asi is a Sanskrit dictum repeated nine times in sections 6.8 through 6.16 of the Chandogya Upanishad. It is traditionally translated as "That thou art" or "That you are," equating the individual Self with the ultimate reality (Sat or Brahman). Scholars Brereton, Olivelle and Doniger argue the correct translation is "That's how you are," meaning Svetaketu exists by means of the same invisible subtle essence as all other creatures.
The Chandogya Upanishad has eight chapters, called Prapathakas. The first two chapters focus on speech, song and the syllable Om. Chapters three through five cover teachings about the universe, life, mind and ethics, including early formulations of dharma and ahimsa. Chapters six through eight address metaphysical questions about the nature of reality, the Self and the identity of Atman with Brahman.
Adi Shankaracharya cited the Chandogya Upanishad 810 times in his Vedanta Sutra Bhasya, more than any other ancient text. Other major commentators include Madhvacharya, Dramidacharya, Brahmanandi Tankacharya and Ramanujacharya.
Satyakama, the son of Jabala, seeks admission to the school of the sage Haridrumata Gautama and honestly tells the sage he does not know who his father is, because his mother had gone about in many places in her youth. The sage accepts him as a student, declaring that this honesty is the mark of a true seeker of Brahman-knowledge. Satyakama tends four hundred cows until they multiply to a thousand, then receives teachings from a bull, a fire, a swan and a diver bird before returning to his teacher.