Balderdasq: So I already know that in order to get the light side ending, I need to avoid killing innocents and using dark side powers. However, a few bystanders have already been killed either on accident or because they were blocking a doorway I needed to go through. If I solely focus on light side powers now, will I still get the light ending or will I need to restart in order to get it?
SCPM: You can still get the light side ending, there is a major decision you need to make during a certain cinematic in the second half of the game that will determine which ending you get.
There is no "decision" to make during a cinematic. It's determined solely by the decisions you made throughout the game, and the result is revealed during the cutscene.
Fortunately, as long as you picked mostly/all light side powers, collateral damage to a few civilians shouldn't be enough to make you fall to the dark side. :)