We are in the middle of the Holy month of Ramadan and it is such a special time to visit Egypt. Try if you can to get invited by a family to break the fast at sunset. They do not mind at all that you are not fasting and love to share this special time with you.
I love being in a country so united in a religious festival, the nearest thing I have experienced before is Easter in Cyprus.
How does it affect the tourist, well hardly at all. Hotels etc try and use Christian staff where ever possible to serve alcohol but don't be surprised in small hotels to find no alcohol or the staff asking you to help yourself. They prefer not to even touch it during Ramadan. It is not a good idea to be on the road around sunset as road regulations tend to be tossed aside in the rush to get home for Iftar. Certain government and official places like passport offices and banks close early and some of the sites have special Ramadan openings.
If you are on a full day trip be considerate to your driver or guide and insist that they stop and break their fast. They do not mind you eating or drinking in front of them but I prefer to be discreet but woe betide you if you lit a cigarette.
This is not the time of year to disagree with an Egyptian man during the day!!! Wait until he has broken his fast before nagging him about chores not done.
Soon it will be Eid and everyone gets new clothes and the children get money. Egyptians try and pay all their debts and make sure everything is up to date Mon wise so that everyone can have a good Eid. I you give someone a good tip so they can enjoy a good Eid your kind gesture will be much appreciated.