I think one thing people are getting confused about is the "light side"/ "dark side" points. Now I'm not in the Beta but from what the developers have hinted at it's really not light and dark points like in the force. By this I mean the "light side" option for a Sith wouldn't be to help the Jedi council or something like that but would be to benefit the Empire above yourself.
For example (and I'm totally pulling this out of my head, nothing NDA breaking unless I'm just damn good at hypothetical situations) you're a Sith. You go into a moff's territory and discover that he is running a highly illegal fighting arena between peasants. If what I understand is right the "light side" option would be to turn him over to the authorities and the "dark side" Option would be to accept his bribe and get a cut of the profits. I think the names "light side" and "dark side" in the game are just an easy way to refer to it. Think paragon and renegade if you have to.
Personally I intend to make my decisions the same way I do in Mass Effect, I'm going to base it off what I feel the character would do in the situation to serve him best. I mean I'm not going to go with the "slaughter 90 babies b/c that dude sneezed" option, but I would definitely go for the slaughter 50 guards so you can gain access to a rare lightsaber crystal option. One is "evil for being evil" the other is "evil to gain something". Sith to me aren't about being evil just so they can go "muahahaha I'm one evil bastard" as in the Sith code located on Page 2 shows it's all about gaining personal power and accepting your emotions.