Short answers, pulled from the story.
A Roman grammarian taught the ancient poets, including Homer and Virgil, along with the correct way of speaking. The role covered accurate reading aloud, the explanation of literary devices, etymology, and the critical study of literature. Students studied under a grammarian between basic language instruction and the advanced study of rhetoric.
According to Suetonius, grammar was introduced to Rome when Crates of Mallus, visiting from Pergamum, broke his leg and gave frequent lectures on the subject during his convalescence. Before that, the study of grammar was not practiced in Rome, a situation Suetonius attributed to the city's martial character and lack of free time for literary education.
Around 100 BC, Dionysius Thrax defined grammar as an "acquired expertise of the general usage of poets and prose writers." He identified six elements: accurate reading aloud, explanation of literary devices, comments on subject matter, comments on etymologies, working out analogical regularities, and the critical study of literature.
Grammarians in Rome were exempt from local taxes. By tutoring the children of wealthy families, they also gained access to prominent households; Marcus Antonius Gnipho, for example, was part of the household of Julius Caesar. Despite being esteemed and well paid as a class, few individual grammarians achieved lasting financial success.
Twelve of the twenty grammarians described by Suetonius in De Illustribus Grammaticis had originally been slaves. Their rise to respected teaching positions illustrates how the profession could offer social mobility despite humble or captive origins.
Latin grammarians, like their Greek counterparts, came from across the Roman Empire, including Syria, Spain, Gaul, Athens, and Italy. Many of the best teachers also traveled out of Rome to bring grammar instruction to the provinces.