Robert,
        The "n-word" reference you're looking for occurs in a review
of Pudd'nhead Wilson in the 1904 Booklover's Magazine.  The review
is by T. M. Parrott.  It's available in the Norton Critical Edition
of Pudd'nhead Wilson.
        The Hemingway statement on Twain occurs in Green Hills of
Africa (1935); it's on p. 22 of the Scribner paperback edition.  The
paragraph is as follows:  "All modenr American literature comes from
one book by Mark Twain called Huckleberry Finn.  If you read it you
muéÜst stop where the Nigger Jim is stolen from the boys.  That is
the real end.  The rest is just cheating.  But it's the best book
we've had.  All American writing comes from that.  There was
nothing before.  There has been nothing as good since."  Hemingway
goes on to discuss Crane and James.

Hope this helps.

Donna Campbell