Short answers, pulled from the story.
Jacopo Peri wrote Dafne around 1597 for an elite circle of literate Florentine humanists known as the Camerata de' Bardi. The work itself is lost but a later score called Euridice from 1600 survives today.
Public opera houses emerged in Venice during 1637 when ticket sales supported seasonal performances. Francesco Cavalli helped spread these Venetian styles throughout Italy after moving there from Mantua.
The bel canto style flourished in the early 19th century with Rossini Bellini and Donizetti creating florid vocal lines requiring supreme agility. Rossini's Il barbiere di Siviglia and La Cenerentola exemplified this intricate approach.
Richard Wagner began moving away from traditional tonality with his Tristan chord in the mid-19th century. Arnold Schoenberg and Alban Berg pioneered true operatic modernism using atonality and dodecaphony shortly thereafter.
Anna Renzi emerged as the first major female star or prima donna around the mid-17th century. Farinelli and Senesino became international stars possessing extraordinary vocal virtuosity during the 18th century before her time.