I'll contribute some scribblings.
Debating angle yet though.
Initial thoughts: Timeline, yay. Empire agent restriction to NPC, boo.
Further thoughts: I always thought it'd be a good idea/way to start a group SL game off with a bang like a battle rather than the slow background ramp up avenue we usually take. In order to have a genesis point in which everyone could be present and creates a lot of loose threads to be strung together and give all characters a unifying subject, you could have a planet that is being subjugated by the Empire. Maybe the story begins in the midst of bombardment, leading in to landing operations. On the surface you could have all sorts of geopolitical factors that immediately come in to play and shape character choice/drive. I like to look at real world scenarios and spin off that, maybe the world is in midst of civil war between ancient monarchy and aspiring democratic nationalists, maybe there's a huge alien population on the planet that aren't indigenous but were resettled refugees or something, they've been around thousands of years but not as long as the humans. Perhaps aliens make up substantial support base of the democratic nationalists, so the monarchy has invited the Empire to help crush the Civil War and win it for them. Empire obliges, and in predictable fashion pretty much indiscriminately assaults the planet, Monarchists and Nationalists, civilians alike suffering the Imperial onslaught.
Presumably then, you end up with individuals with Alliance character leanings to emerge from the Nationalist corner, or maybe the brutality begins to sway their loyalties from the Monarchists. Or maybe they are just some self employed traders/smugglers/whatever that happen to be trapped a regional starport on the surface when the Empire blockade/bombardment begin. Perhaps part of the Empire's eagerness to oblige the Monarchist request is outspoken media critics on the planet of the New Order. Making the Empire especially interested in taking a front line role there. Anyways, the idea is that this origin point would only last as long and be indepth as we desired to make it. It could be a quick thing that just sends us all scurrying away from there, or maybe some of us chasing some of us who scurry from there or it could be a longer thing that is like an opening chapter to a longer saga.
Just beginning of a thought.