You've sketched out well the various periods of Augustus' life, but I was thinking about possible additional threads. Besides chronological periods, there are definitely themes that we might want to develop in the future.

One that seems obvious to me is the mechanics of how Augustus turned a warlord oligarchy into a tamed civil service. It isn't quite a "legacy" - it's a move from Republic to Empire. Perhaps sub-parts could include (this ARE just suggestions, do what you think best!)

The Triumvirate
The Struggle with Antony
The Settlements of 27 and 23 BC
The Succession Problem
The Inclusionary Empire


The latter intrigues me because Augustus really DID accomplish what Julius Caesar tried but did not live to accomplish - the breaking of the stranglehold of the Optimates and Roman nobility over the powerful positions of government, so that by the time Augustus died, Equites and provincials from all over the Empire were so naturally in places of power and influence that people probably had forgotten just how difficult, before that, a "new man" would find it to achieve anything politically.

And the Succession issue is the ONE thing that Augustus couldn't fix and it haunted all later emperors (the gods know, he TRIED).
Just some thoughts!