To answer the debate of the Justicars' allegiance, one can discern that they are the "tea-party" of the Republic.
Anyways, the ideas aforementioned are terrific, however, I find them too similar to classes presently available. A very appealing notion is being an android. It could be a completely different experience that hasn't been explored as both a new class and species (or model--if you will). Famous droids such as Guri, IG-88, HK-47, and C-3PX remove the notion of droids being quirky side kicks and comedic relief. Imagine this: Imperial scientists perfect an android replicant to infiltrate SIS or you're a Republic magna droid with a glitch and takes on their own personality. Possiblities are endless and would give variety to different droid models and classes that doesn't follow the archetypical model of the hero.