Short answers, pulled from the story.
Egyptian temples were built as houses for the gods, serving as places where divine presence could inhabit the human world. Priests performed daily rituals there including feeding, dressing, and honoring a cult statue believed to be inhabited by the god's spirit. Temples also functioned as major economic centers, owning large tracts of farmland, livestock, and in some cases fleets of ships.
Access was strictly limited based on a hierarchy of ritual purity. The innermost sanctuary was accessible only to the highest-ranking priests. Laypeople were generally confined to outer courts, doorways, and hypostyle halls during festivals. Niches in the exterior wall at the back of the temple provided a space where ordinary Egyptians could pray as close as possible to the god's dwelling.
Temples accumulated wealth through royal donations, private gifts of land and goods, and their own extensive agricultural holdings. The largest temples employed tens of thousands of people and owned farmland, desert expeditions for salt and minerals, and trading fleets. Richard H. Wilkinson noted that the temple estate often represented no less than a slice of Egypt itself.
Temple cults died out between the fourth and sixth centuries AD under increasing Christian persecution. Some temples were converted into churches, while most were abandoned and stripped of stone for building material. The last known hieroglyphic inscription is graffiti at Philae dated to AD 394, and the last Demotic inscription there dates to AD 452.
During festival processions, people could seek answers from the god by watching the movements of the divine barque as priests carried it on their shoulders. Gestures of the barque, including tipping toward tablets with possible answers, were interpreted as the god's reply. Questions ranged from finding lost objects to choosing candidates for government appointments.
The construction of the Aswan Dam in the 1960s threatened to submerge the temples of Lower Nubia beneath Lake Nasser. A United Nations effort relocated some monuments to higher ground. The Egyptian government gifted several others internationally, including the Temple of Dendur, Temple of Taffeh, and Temple of Debod. Several temples nonetheless disappeared beneath the lake.