These stuff have been solved in years. If you have been taught by a teacher, go back to him and slap him in the face and ask for a refund, he didn't teach you properly. If self-taught, pls lurk more on a lot of 3d forums.The black outline you usually assign the property to the camera now which will trace all the surrounding objects, the flipped normals on an slightly enlarged model can kind of fuck with shit in unintended ways at least with what I've done with it. The bends in the arms and legs tends to be the most noticiblebecause you still have to do the envelopes for it, for facial closeups it's fine but if you're doing full body that's when it rears it's head with problems. Also stuff like aprons and other long flowing clothes you'll have intersecting polys more frequently.
The one drawback of the camera tracing stuff is that at a certain distance it will either have all the objects be all black in the distance or not render right.
I am not going to explain it in huge details, and the post earlier is just a quick explanation. But to give a hint on how to solve on what you are agonizing about: The outline is sometimes part of the mesh itself or actually part of the texture