Short answers, pulled from the story.
Brahma created himself from a golden egg known as the Hiranyagarbha that emerged from an eternal ocean of darkness. This self-emergence event marks the genesis of the universe in Hindu cosmogony and establishes Brahma as the self-born Svayambhu.
The four heads of Brahma point toward the cardinal directions and symbolize the four Vedas: Rig, Yajur, Sama, and Atharva. These heads represent the omnipresence of knowledge and ensure that no part of the universe escapes his creative gaze.
Brahma is rarely worshipped because Shiva severed his fifth head for dishonesty during a dispute over truth and power. This act cursed Brahma to a secondary role in the Trimurti and stripped him of active worship except at the Brahma Temple in Pushkar, Rajasthan.
Sarasvati is the wife of Brahma and the goddess of knowledge who embodies the energy that drives his actions. She complements his Rajas quality of passion with her Sattva quality of balance and purity to shape the physical world.
By the 7th century CE, Brahma had lost his significance and was overshadowed by the rise of Shaivism and Vaishnavism. This theological evolution redefined the roles of the Trimurti and made Brahma a secondary creator dependent on higher gods like Vishnu or Shiva.