Yes, but you may pay more to mail the package if it only weighs one ounce, and you use a one ounce Airmail stamp.
No. It's enough to write "Par Avion - By Airmail"clearly in the top left hand corner of your envelope.
As long as you have the correct postage you can use 'regular stamps' to post to anywhere in the world. If I want to send a letter and it costs $2:40 then I know I need 4 stamps @60c value each , which is the domestic rate in NZ. Otherwise I go to the Post Office and buy a $2:40 stamp.
No, you have to use stamps from the country of origin of the mail. In this case you will have to use Italian postage stamps.
Yes, every country uses postage stamps.
Of course you can. As long as the total amount of postage equals the first class rate. All mail is sent air these days.
How possible it is. For Collection, one can use US postal stamps. But for regular use for letters or parcels not possible. Bulgaria is not a state of USA
No. When mailing items you use the stamps of the country of origin.
England as the first to use postage stamps, starting in 1840.
The entire purpose of the Forever Stamps was that you can use them for one ounce of First Class Postage forever. No additional postage is necessary.
ofcourse they do
You can use forever stamps for an ounce of postage forever. They never lose their value for one ounce of postage.
They are still valid for use as postage as long as they add up to the proper postage. If you check USPS regulations Postage due, special delivery and certified mail stamps are NOT valid as payment for postage.