Short answers, pulled from the story.
The Augustus of Prima Porta is a full-length marble portrait statue of Augustus, the first Roman emperor, standing 2.08 meters tall and weighing 1000 kilograms. It blends Greek sculptural ideals with Roman political imagery. It is now displayed in the Braccio Nuovo of the Vatican Museums.
The statue was found on the 20th of April 1863, during excavations directed by Giuseppe Gagliardi at the Villa of Livia in Prima Porta, near Rome. The German archaeologist Wilhelm Henzen announced the discovery the same year in the Bulletino dell'Instituto di Corrispondenza Archaeologica.
The commission remains uncertain. One theory holds that Tiberius ordered it; he is depicted on the cuirass as the diplomat who recovered Roman legionary eagles from Parthia in 20 BC. Another theory credits Livia, Augustus's wife, who may have set up the statue after his death in AD 14.
The breastplate shows the Parthian king Phraates IV returning Roman legionary standards to an armored Roman, commemorating the recovery of eagles lost by Crassus in 53 BC and by Mark Antony in the 40s BC. Surrounding deities include Caelus, Apollo, Diana, Sol, and Ceres. Two Sphinxes on the shoulders allude to Augustus's defeat of Cleopatra.
The statue was almost certainly painted when it was made. Vincenz Brinkmann of Munich used ultraviolet light in the 1980s to find surviving traces of pigment. The Vatican Museums produced a painted reconstruction based on findings from the 1999 cleaning, though art historian Fabio Barry criticized it as unsubtle and exaggerated.
In classical antiquity, bare feet were reserved for images of gods and heroes, not military commanders. Depicting Augustus without sandals places him in divine or heroic territory without explicitly claiming godhood. The barefootedness may also indicate the statue is a posthumous copy, since Augustus reportedly resisted depictions of himself as a god during his lifetime.