Short answers, pulled from the story.
The title legatus Augusti pro praetore refers to a provincial governor who governed some Imperial provinces of the Roman Empire during the Principate era. This official typically commanded larger provinces or those where legions were based under direct imperial control.
A legatus Augustus was always a senator of consular or praetorian rank who had previously held the office of consul or praetor before taking this post. Exceptions existed for smaller provinces like Mauretania, Thrace, Rhaetia, Noricum, and Judaea which were administered by equestrian prefects instead.
In AD 68, fifteen out of thirty-six provinces were ruled by legati Augusti including Hispania Tarraconensis, Lusitania, Gallia Aquitania, and Britannia among others. These territories fell under the command of officials selected directly by the emperor rather than elected by the Roman Senate.
The legatus Augustus held dual roles as head of administration and chief judicial officer while serving as commander-in-chief of all military forces within the province. His authority covered both civil governance and martial operations simultaneously without any other official sharing this combined power over civilian life and army movements.
The governor of Egypt held an unparalleled status because a praefectus Aegypti was an eques member of a social class between plebeian and patrician who commanded legions stationed in that region. This exception broke the usual rule requiring consular or praetorian background since Egypt remained unique as the empire's breadbasket and source of grain.