To elabortate a bit on your conclusions

• Lighting is too strong for GC
  The interaction between the lights is wrong, putting most of your figure in shadows. It is Ok to have more lights in a scene, but start with ONE true white light, and build from there. Make area renders to test small variations.
• With IDL and in a closed scene, often one light is all you'll ever need.
  The rest of the light coming from diffused IDL light bouncing off all other objects in the scene. (As is the case in real life.) Everything reflects light in one way or another. If something does not reflect light, like a black hole in space, we would not be able to see it;

• Optimal GC requires a closed environment; use BB's envirosphere-thingy
  IDL works best in a closed environment; See above.
  Indirect Light has to come from somewhere. It needs something to come from. It needs a base. One single figure in an empty space, and you have no other actors, so no other light sources. So no IDL exept for the figure itself.

• GC should be 2.2 for EITHER materials OR render options, but not both; one or the other should be at 1.0
  Just tell colored textures to use render gamma when you load them.  And set GC for the scene in the renders options.

• Grey maps (bump, trans, etc) should be at GC 1.0
  Correct, bump, displacement and transmaps should stay at Gamma 1

Sugestion:
Put the figure above in BB's sphere, and put one infinite true white light on it.
See what happens.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!