Short answers, pulled from the story.
Gregorius served as magister libellorum to emperors Carinus and Diocletian during the 280s and early 290s. No surviving document confirms his full name or personal background beyond these professional duties.
The work emerged between 291 and 294 AD though the exact calendar date remains lost to time. It spans constitutions issued over a century and a half from the 130s through the 290s AD.
Scholars estimate the original work contained anywhere from fourteen to sixteen books depending on their interpretation of fragmentary evidence. Most modern researchers lean toward fifteen books as the most likely count.
Emperor Justinian absorbed the Gregorian Code into his own Codex Justinianeus with the first edition taking effect across Roman Balkans and eastern provinces in AD 529. By mid sixth century the original Gregorian text had been consigned to obscurity over most Mediterranean regions.
Simon Corcoran and Benet Salway announced discovery of seventeen fragments believed to be original version at University College London on the 26th of January 2010. Researchers accessed these materials shortly after initial announcement on the 27th of January 2010.