Looks like a mixed breed to me; so mixed that I don't know what breeds went into her. Must have had mixed parents for several generations. As for age, I'd say she is about a year old, maybe more. It gets harder to tell the age once hens get older than about six months, since they don't change much in appearance after that point.
Mixed breed hen. Might have some Delaware in her, or some Light Sussex. Its possible that she has many breeds in her, and is from crosses of crossbreeds.