A nice analysis of the ethnic and linguistic make up of the eighty million people Egypt is found here, and its religious diversity is analyzed here.
Linguistically, most Egyptians speak one of two dialects of Arabic which are described as being roughly as similar a Spanish and Portuguese, one of which (Sa'idi) is spoken in Upper Egypt (the Southern part of the Nile Valley) and the other of which (Egyptian Arabic) is spoken in Lower Egypt (the Northern part of the Nile Valley). A Libyan dialect of Arabic is spoken on the Mediterranean coast beyond the Nile Delta region. And, Bedouin dialect of Arabic is spoken in the Sinai.
There is also a pocket of the Nile Delta where Greek is spoken, a small community on the Southern Red Sea Coast that speaks the Cushitic Beja language, and an oasis community in the Western Desert that speaks the Berber Siwi language. In the far South of the Nile Valley of Upper Egypt two Nubian (Nilo-Saharan) languages are spoken.
In addition to these linguistic minorities there are communities of Abazas, Turks, and Dom (Gypsies). "The Abazas . . . are a Circassian/Abkhazian people whose ancestors fled Russian assaults in the Caucasus in the 19th century; although they have long maintained a distinct identity in Egypt[.]" Estimates of the Dom population range from tens of thousands to a million, an estimate complicated by the apparently common practice of Dom publicly identifying as Palestinian to avoid discrimination. Egyptians who are not part of one of these minorities speaking one of the two main Egyptian Arabic dialects make up about 91% of the Egyptian population.
There are significant Christian minorities in Egypt, perhaps ten percent of the total in many Nile Valley and Northern Red Sea coastal areas, mostly Coptic Christian (perhaps seven or eight million in all), but perhaps a quarter million of whom are many other types of Christians (they seem to be concentrated around the Nile Delta), and there is apparently a Shi'ite minority in parts of the Nile Valley of Upper Egypt whose numbers are a matter of great dispute but may make up as many as a million people. Most Egyptians, of course, are Sunni Muslims and are generally not a part of the Wahhabi sect that dominates in Saudi Arabia and is evangelized by the Taliban.
In an international context, Egyptian Sunni Muslims are on the conservative/traditionalist end of the the scale on "social issues," although not necesarily as extreme as Wahhabi sect Muslims. Gender segregation in the workplace is favored by a narrow majority and most Egyptians favor the use of harsh Islamic law punishments for offenses like adultery and theft.
Still, despite pockets of diversity, the overall picture is of a relatively homogeneous core Egyptian population in the Nile Valley split mostly between Upper and Lower Egypt, with small, mostly geographically compact minority populations on its periphery. Upper Egyptians and Lower Egyptians, Sunni Muslims, Shi'ite Muslims and Coptic Christian alike, all have a strong Egyptian national identity, muted somewhat by a sense of also belonging to larger Muslim and Pan-Arab communities.
Any reasonably democratic process will produce a parliament in Egypt dominated by Sunni Muslims who speak one of the two main Arabic dialects of Egypt, with the more urban Lower Egyptian Sunni Muslims probably making up a majority or close to a majority.