Thank-you very much for the swift reply.
(1) OK, I will just copy all of them over - I was just puzzled by the fact that the Readme does not mention glxtokens.h. I think I have all the other libraries (eg Mesa) I need- so long as I don't have to get versions which are in some way nV modified.
(2) I am sure that they *are* the ones from xfree 86. I wondered why the nV installer did not automatically overwrite them at the same time it was installing itw own stuff to /usr/lib - should it not have done so?
(3) I have a general understanding of the role of (.a) libs - I guess I was just being obsessive about having everything neat and tidy. Also, I did not realise that if I delete the (.a) libs then compilation via (.so) will be forced - I thought that some compilations would just fail if the code required a (.a) and it was missing.