They dropped the KO- from KOTOR, apparently. You'll have "companions" which are essentially characters which are members of your party. Or, really, just your party. I wonder how grouping works...
Can I play alone?
While there are some tasks that cannot be completed without the cooperation of others, the majority of the game can be accomplished by playing alone.
How does Star Wars: The Old Republic differ from other MMO titles?
Star Wars: The Old Republic will be similar to other MMOs but with several key innovations. Traditionally MMOs are built on three pillars; Exploration, Combat, and Progression. We at BioWare and LucasArts believe there is a fourth pillar: Story. Our mission is to create the best story-driven games in the world. We believe that the compelling, interactive storylines in Star Wars: The Old Republic are a significant innovation to MMOs and will offer an entertainment experience unlike any other.
Will I be able to play on the Light or Dark side of the Force?
Yes, during character selection you will align with the Republic or the Sith Empire. In addition, throughout the game you will also be faced with many decisions which can change your path down the Light or Dark side of the Force.