And an aditional, yet related question...

Lets say I have a humanoid model character with bones, and I want to make several characters using this same model by just changing skins.

But lets say one character has a third arm or something sticking out of their chest...

I would have to have the bones set up to include this extra arm... but the other models won't be using this bone.

Is it any big deal to have extra bones in a model that Arent being used?

And quite opposite to the previous question in this thread...
If it was AFTER i completed the animations, will it cause any problems to remove an unused bone ?