A little help with Skinning

I am sort of a newb with skinning but I have a quick question.

If you save your new file as a .tga doesn't it overwrite the skin u reskinned?

If you renanmed it, then you coudlnt add it to a map?

So are you limited to how many skins you can use? To the number of skins there are to edit?

It 'overwrites' (= loads instead of default one). To add a renamed skin or multiple different skins, you must have custom models with different pathnames to textures.