I think the strings.h problem is because you probably ran the
configure script with mingw prior to your MS Visual Studio build. It
sets up a pg_config.h within $PG/src/include which is defined for
mingw not for MS Visual Studio. If you simply delete that file, then
the win32.mak makefile will correctly overwrite pg_config.h.win32 to
the pg_config.h.
That should get you past the problem.
-Tony