Yes, every country uses postage stamps.
Sweden
Greece
Hungary
Japan is also called Nippon.
Switzerland - official name: CH, confoederatio helvetica
Deutchland
Romania is the country that marks their stamps posta romano.
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).
Saugt schaukelt Deutchland habe ich recht nichtmakes absolutely nop sense but translates as suck swing Germany am I right not.