Merge touching faces on model I have a model like in the following image:



There is a mesh for this object made of many individual cubic boxes. Every individual box has its own 6 faces, so where they touch with another box, there are 2 faces on the same place touching (and some of the cubes intersect each other, so their faces are inside each other). 

I want to simplify this model and


Remove internal faces (those touching each other)
After removing faces, also remove unnecessary vertices


What's the way to do this in Blender? (using version 2.66)
I suggest to


Join the objects into one object / mesh (select all cubes in Object Mode, CtrlJ)
Enter editmode, select all A (if not already) and Remove Doubles (in W menu)
Deselect all A
Select > Interior Faces
Delete > Only Faces X