Former Sith, sure. Just please remember to tone down force powers. As for plot details.

The Rebel Alliance has grown far more powerful as outer rim Volunteers fill its ranks. The wookies become a major backkng for and surviving Jedi rally to Luke Skywalker as there new grandmaster. In response the Grand Moffs have formed a council with them and the Inquisitors controling Imperial government. The moffs concede systems to the rebels to bolster there own fleets and garrisons. They continue to claim that the Alliance is not a government and is made of pirate scum.

As to your mission, you were selected to join a task force attacking the head of Imperial power. Your first goal will be to board a Imperial Star Destroyer borrowing a shuttle you will reach the ground from there you will gain allies and attempt to remove the heavy Anti-ship guns that protect the planet. Other objects are securing the Jedi temple and Senate building. You may also sabotage and slander Imperial lies as you see fit.