It's a party-based RP.

The 'Sith' character is more like a rogue Jedi, or a Dark Jedi I guess, I need to do some research on that.  He's in no way aligned with what the actual Sith are planning, nor does he want what [i]they [/i]want.  The Sith character merely uses the Dark Side of the Force as a means to his own ends; it is a powerful ally, and he knows this, so he's going to use it.

The Jedi has something he needs, and once he gets it the two will decide that perhaps it is a good idea to stick together.

Also, I doubt the Jedi would outright kill someone, as they don't like to do those sort of things.  But don't forget, if she is rescued by the Sith character, what exactly is going to cause her to kill him?  Especially when she needs him just as much as he needs her.

The others would have their own reasons.  A bounty hunter may have been promised a large sum, a smuggler may be granted whatever.

The droid would be protocol/humanoid, but he would have programming that could give him similar abilities as an Astromech.

I would have wanted it to be Old Republic era, after or even perhaps during the Mandalorian Wars - though that would cause complications with the Bounty Hunter character and the Jedi.