you need to apply to the Egyptian Embassy or Consulate for a pre-entry
tourist visa but if you are from European union, Australia, New Zealand,
Korea, Norway, Japan, Russian Federatio, Ukraine, United Kingdom,
Macedonia, Canada, united states, Serbia, Croatia, Georgia you can get your
tourist visa upon arrival in Egypt.

Yes you can do but you need to obtain an extension from the Mogamma
building in the Tahrir Complex or the equivalent governmental offices in
another city outside Cairo.

Tourist visa is required to visit other cities in Egypt because the visa for
Sinai allows the tourists to visit Sinai Peninsula only.

If the tourist doesn’t hold a residency permit so he should apply for a visa
from the Egyptian embassy in the country that issued his passport.

Yes, if you left Egypt to visit another country you will need another visa.