I've just gotten back and am still reading through the discussion (I'll probably not be able to refrain from commenting here and there!), but let me join the others in thanking you. 
     Then, one brief comment on the question you raise in this summary: As a general rule Tolkien was very willing to invent more "background information" than he would possibly need.  Some authors are like that.  Sinclair Lewis used to prepare for his novels by drawing up maps of the towns they were set it, writing mini-biographies of minor characters (out of which only the odd bit of information would actually enter the novel), even drawing floor-plans of houses (including rooms in which no scenes, in the end, were set).  The result, at its best, is the density of detail in Main Street.  Tolkien seems to have been an author who worked in a similar fashion and who went to elaborate lengths to design a language and a history for each people of Middle-earth.  This density of detail, this presence of layer upon layer of history, make the LotR such a believable book.

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All that is gold does not glitter,
Not all those who wander are lost;
The old that is strong does not wither,
Deep roots are not reached by the frost.
From the ashes a fire shall be woken,
A light from the shadows shall spring;
Renewed shall be blade that was broken,
The crownless again shall be king.