Cannot mirror bones, weight mapping impossible First time using Blender, I have watched and read several tutorials on how to add bones, center and all the basics. But I was never able to get the mirror tool to work.

I then just made with what I could and realigned the duplicate. After putting days of work in I finish only to find out that since it's asymmetrical it can't have weight mapping. 

I still have all the limbs as individuals so if I could mirror it would it work? or because the model itself is asymmetrical I can't do it? Would weight mapping work?
You can absolutely have weight mapping in asymmetrical meshes. If the automatic weight assignement fails, probably is because the mesh is not manifold: maden of spare parts, or it has holes or bad junctions, or doubles, or something like that.

In those cases you can either improve the topology of your mesh or go with manual weighting (weight paint or weight assign in the properties panel, vertex groups section): or - even better - both.

What do you mean for "mirror tool": the mirror modifier or the mirror option checked in edit mode? Anyway they both need the origin of the object set in the proper position to act as pivot point of the mirroring.
In the mirror modifier check the clipping option for proper behaviour.