Short answers, pulled from the story.
Lorenzo Ghiberti was a Florentine Renaissance sculptor born in 1378 in Pelago, about twenty kilometres from Florence. He is best known as the creator of two sets of bronze doors for the Florence Baptistery, the second of which Michelangelo named the Gates of Paradise.
The Arte di Calimala announced the competition in 1401 and narrowed the field to seven semifinalists. By 1402 only Ghiberti and Brunelleschi remained; the jury could not decide between them. Brunelleschi withdrew to Rome to study architecture, leaving the twenty-one-year-old Ghiberti to complete the commission alone. Ghiberti's panel was technically superior, using less bronze and weighing less than Brunelleschi's.
The Gates of Paradise are the second set of bronze doors Ghiberti made for the east side of the Florence Baptistery, commissioned in 1425 and completed after twenty-seven years of work. Michelangelo declared them fit to be the gates of paradise, a verdict Giorgio Vasari echoed a century later by calling them the finest masterpiece ever created. Ghiberti himself described them as the most singular work he had ever made.
Ghiberti used 34,000 pounds of bronze to cast the first set of doors, at a total cost of 22,000 ducats. His first casting attempt failed; the successful cast came on the second try.
The Commentarii contains what is considered the earliest surviving autobiography by any artist. Ghiberti traces the development of art from the time of Cimabue through to his own work, and describes his aim in the second Baptistery portal as seeking to imitate nature as closely as possible in both proportions and perspective. The text also quotes extensively from Alhazen's Book of Optics and served as a primary source for Giorgio Vasari's Vite.
Among the artists who worked in Ghiberti's workshop were Donatello, Masolino, Paolo Uccello, and Antonio del Pollaiuolo. Donatello is known for one of the earliest examples of central-point perspective in sculpture, and Paolo Uccello is commonly regarded as the first great master of perspective.