Short answers, pulled from the story.
Nephthys was an ancient Egyptian goddess and a member of the Great Ennead of Heliopolis, born of Nut and Geb. She was associated with mourning, death, darkness, protection, magic, embalming, childbirth, and beer. She was typically paired with her sister Isis in funerary rites as a protectress of the mummy.
Nephthys is the Greek form of the Egyptian epithet nbt-ḥwt, usually translated as Lady of the House or Lady of the Temple. The name was written using hieroglyphs combining the sign for the sacred temple enclosure (ḥwt) with the sign nb, meaning mistress or lady, placed on top.
Nephthys assisted her sister Isis in gathering the dismembered portions of Osiris's body after his murder by Set. She was one of the four Great Chiefs ruling in the Osirian cult center of Busiris, and at Abydos she joined Isis as a mourner in the shrine known as the Osireion.
The Pyramid Texts identify Nephthys as the nursing-mother of Horus, in contrast to Isis who is his birth-mother. As the primary nursing mother of Horus, Nephthys was also considered the nurse of the reigning pharaoh himself.
Ramesses II built or refurbished a temple called the House of Nephthys of Ramesses-Meriamun in the town of Sepermeru, located midway between Oxyrhynchus and Herakleopolis near the Fayyum. According to Papyrus Wilbour, this was an independent land-owning temple with its own prophets and priests, and a second House of Nephthys may have existed in the town of Su.
A near life-sized basalt statue of Nephthys, currently housed in the Louvre, was originally stationed at Medinet-Habu for the pharaonic Sed-Festival. It was later moved to Herakleopolis and the temple of Herishef, and its inscription was re-dedicated from Nephthys Foremost of the Sed Festival to Nephthys Foremost of the Booths of Herakleopolis.