Hi Pieman:

Can't help you with the meaning of Stepford, but I can provide some brief quotes about the film, courtesy of Halliwell:

"It was hard to tell Katharine Ross playing a robot from Katharine Ross playing a normal housewife." (Les Keyser, Hollywood in the seventies)

"The first women's lib gothic -- hardly the landmark the world had been waiting for." (the late Pauline Kael, New Yorker)