There are two recent [1999]biographies of Saint Saens (in English) that I
know of.

Brian Rees: Camille Saint-Saens A Life. London: Chatto & Windos[1999].

Stephen Sudd: Saint-Saens: A Critical Biography.

I've read all of the first, which is a very good general biography,
covering life, career and compositions, without going into much musical
analysis.  Stephen Sudd's book is also a biography but does more analysis
of the music.  My guess is that the first was aimed at the general market
for biographies of cultural figures, while the second is a bit more for the
specialist market.  I thought both were good books about Saint-Saens, who
is one of my favorite composers.

As for books by him, a collection of his writings was translated in the
early part of the century as Musical Memories.  I remember enjoying it a
few years ago.

Gary