Sure you can do, banks and exchange offices which you can use for that are
everywhere. There are also many touristic shops and restaurants accept
Dollars or Euros and give you rates of your currency to the Egyptian pound
are relatively close to the official ones.

Yes you can use them as large numbers of places accept them such as hotels,
touristic shops, restaurants, and café shops, so they are widely used in Egypt.
Visa, Master Card, and American Express the most common types of credit
cards are used in Egypt