1. I believe the primary audience is to women and girls. The secondary audience would be to anyone who views this image. 
  This image is to encourage interaction between the ages.  Girls need mentors and older women who love and direct them in life.  
2, Changing this picture to black and white or color would not change the perception of this picture. If anything it may convey a more serious message of the need for involvement.  This picture shows the girls leaning into the older person and smiling at the person taking the picture.  Everyone seems relaxed, so the color change would only have minimal affect.