Short answers, pulled from the story.
King Menes is credited with founding Memphis by diverting the Nile River to create his capital. Some Egyptologists identify this legendary figure as the historical Narmer who conquered the Nile Delta around 31st century BC.
Manetho recorded that King Menes founded Memphis in the early third century BC though archaeological evidence suggests events occurred much earlier. The traditional narrative places the conquest of the territory around 31st century BC during the Early Dynastic Period.
The Memphite Triad consisting of Ptah, Sekhmet, and Nefertem formed the main focus of worship in the city. The Great Temple of Ptah known as Hut-ka-Ptah served as one of the three foremost places of worship alongside Heliopolis and Thebes.
Saqqara serves as the most famous necropolis for Memphis containing funerary rock tombs mastas temples and pyramids. The Serapeum located northwest at Saqqara holds the majority of known Apis statues with burials dating back to the reign of Amenhotep III.
Memphis declined following the rise of Thebes and the New Kingdom before falling into second place after Alexandria was founded. The city lost its status permanently when Alexandria opened onto the Roman Empire and became the most important Egyptian city under the Roman rule.