Short answers, pulled from the story.
The four major naturally occurring estrogens are estrone (E1), estradiol (E2), estriol (E3), and estetrol (E4). Estradiol is the most potent and predominant during the reproductive years; estrone becomes primary after menopause; estriol predominates during pregnancy; and estetrol is produced only during pregnancy.
Adolf Butenandt and Edward Adelbert Doisy independently isolated and purified estrone, the first estrogen to be discovered, in 1929. Estriol and estradiol were subsequently discovered in 1930 and 1933 respectively.
Estrogen favors a Th2 immune response, shifting immunity toward antibody production and away from direct cellular attack. This makes women generally more responsive to vaccines and less likely to develop cancer, but more prone to autoimmune diseases.
Sudden estrogen withdrawal and sustained low estrogen levels correlate with significant lowering of mood. Clinical recovery from postpartum, perimenopause, and postmenopause depression has been shown to be effective after estrogen levels are stabilized or restored.
Xenoestrogens are synthetic and natural substances found in the environment that possess estrogenic activity. They include synthetic compounds such as bisphenol A, metalloestrogens like cadmium, plant-derived phytoestrogens, and fungal mycoestrogens. Estrogen excreted from farm animals that enters fresh water systems can cause reproductive dysfunction in fish.
Estrogens drive the pubertal growth spurt and trigger epiphyseal closure, which sets the final limits on height and limb length. They are also responsible for maintaining bone mineral density throughout life; declining estrogen during menopause raises the risk of osteoporosis.