If you're trying to only make her arm disappear, weird crap is going to go down. Ya gotta turn off everything if you want her all invisible. (LOL: online hardmode: make Kyle skin invisible)
If you want it to be slightly visible though, I would just use the textures from the shadowtroopers. I think that might be an effect too...don't remember.
Those sort of things, but if you did that I'd make the room look a bit more 'modern clean' to make it fit better. (Just lighten up some of the textures, possibly round up the walls a bit.
FYI: Reference pictures are wildly inconsistent, you might want to specify with some pics of what you would want it to look like (assuming someone is interested). Also, pretty much just looks like Mara Jade to me.
Well preventing clipping would be pretty hard since I can't really think of a way that you could do it without writing your own physics/collision engine. w_force.c sounds like the right one for force powers, but not physics.
I think just making the P a solid black would look great. I made a texture for JKG once that was like 10000x7200 or something like that, was about 300mb big. Lol.