Cairo was the capital of the United Arab Republic (UAR).
Romania is the country that marks their stamps posta romano.
United Arab Republic: UAR United Arab Republic: UAR
UAR Pending investigation
UAR
The country of origin.
No. When mailing items you use the stamps of the country of origin.
Great Britain does not print their name on their postage stamps. The name of the country is not mentioned because United Kingdom was the first country in the world to start postage stamps. However, all of the postage stamps have at minimum a silhouette of the current Queen (or King).
Yes, every country uses postage stamps.
Without knowing what stamps you are refering to, it is impossible to offer a value. Stamps are issued from virtually every country in the world, as well each country issues many different stamps each year.
You use the stamps of the country of origin, which in this case is the US. So the individual pays the rate in their country and their countries postage is affixed to the item.
Suomi is Finland.