Dueling Rings gives some extra credits and experience and one (Or two if you glitch) Bendak pistols.
The credits and exp help a lot of Taris but not so much after taris. Bendak's pistol is helpful if one of your companions uses dual pistols, however you can always get Cassus Fetts Pistol and clone it on Manaan.
First of all, I don't really recommend going through Taris at level 2. The most optimal builds all have at least 4 non Jedi levels. 16 levels as a jedi is more than enough to give you all the Force abilities you'll ever need, so it's far more beneficial to get at least those 4 levels so that you can have some extra feats. Only having 2 non jedi levels only weakens your character, and makes Taris almost unbearably frustrating.
As for what companions you should choose, Mission is truly the way to go. Just give her the two weapon fighting feat and carth's/bendak's blaster to get her AB higher, and those sneak attacks will truly make short work of any opponent. Just make sure that you have Zaalbar or Bastila at the front (Bastila doesn't have the best hitpoints, but she can boost her AC so high that almost every attack against her will miss).