You need to give Marble Pink Egg or Large Pink Egg to turn her back full female from herm.
As for question about Alicornum let me copypaste my brave test PC appearance after extensively usage of Alicornum and having all body parts needed to get whooping 10 points of alicorn racial score. (Not entierly like alicorn from MLP you meantioned but it still can 'poke' enemies with it horn while looking quite similar to them or use enhanced healing spells/soulskills)
You began your journey as a human, but gave that up as you explored the dangers of this realm. You are a 5 foot 11 inch tall male alicorn, with a somewhat thick body that’s covered in slabs of muscle. You are currently wearing your glistening gel-armor plates and comfortable loincloth and using your dragon rapier as a weapon. Your face is almost entirely equine in appearance, even having white fur. Underneath the fur, you believe you have olive skin. It has a somewhat masculine, angular jawline. The shaggy, white mane on your head parts around a pair of very horse-like ears that grow up from your head. You have a medium, white goatee protruding from your chin. One huge and long spiraling horn erupt from your forehead, pointing forward. The weight of it is heavy and ends with dangerous and sharp looking tip.
You have a humanoid shape with the usual torso, arms, hands, and fingers. A pair of large, feathery wings sprout from your back. Though you usually keep the white-colored wings folded close, they can unfurl to allow you to soar as gracefully as an alicorn. You have narrow thighs that blend into your pillar-like waist, and your nicely muscled ass contracts with every motion, displaying the detailed curves of its lean musculature. A long white horsetail hangs from your toned butt, smooth and shiny. Two normal human legs grow down from your waist, ending in normal human feet.
You have two flat breasts, each supporting one 0.2-inch perky nipple.
Your monstrous, flared stallion-cock is 52.2 inches long and 5.5 inches thick. It’s mottled black and brown in a very animalistic pattern. The 'head' of your shaft flares proudly, just like a horse’s.
A fuzzy nutsack filled with two grapefruit-sized balls swings low under your freakish, equine dong. You estimate each of them to be about four inches across.
You have one backdoor, placed between your butt-cheeks where it belongs.