Your main damage will come from zapping everything in sight with lightning, but with all those buff powers you can hold your own in melee just fine. After a few levels you'll have more force points than you know what to do with, so don't worry about the alignment costs. Next priority is energy resistance, valor (if light side), revitalize. Powers: Regardless of alignment, grab the heal, speed, persuade, fear/stun (based on alignment), and lightning sets. Dual weilding is nice because you can stack multiple stat boosting lightsaber crystals.
Weapons: Pick either single or dual weilding, get the appropriate feats and the flurry line. Stats: 10, 14, 14, 12, 14, 14 - On level ups, add to charisma and wisdom. Quick example build of something that will do all conversations, and clear through combat with ease: Just make sure you have 12+ Intelligence (14+ for guardian). This can be done either with being a consular (who gets all these skills) or as any other class by taking the skill proficiency feat. For getting the most out of conversations, all you really need to do is max out persuade and awareness, and repair (repair helps with a small number of conversations, but is essential for crafting, since your repair determines how much you get for breaking things down). Unless you purposely try something weird (blasters only, for example), you shouldn't have trouble. A fully optimized build trivializes most content, especially late game. Honestly, the combat in this game is not that difficult.