I talk too much, so I'll try and be simple with the question....

This question deals with MED...

Lets say I have a human model with bones.
Lets say I have all the bones animations I need already.
Lets say I decided later to add long hair to the model and want it to move/wave appropriate to the models animations

Can I add new bones and and animate them without screwing up
the completed model?

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 ?