No, that is not valid for postage. It was just easier to print them that way. Make sure you use a real postage stamp on your letters.
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
The stamp has to be accepted where you mail the letter. If you are mailing in Canada, you need a Canadian stamp. If you are in the US mailing to Canada, you can use a US stamp.
From the US the cost is 98 cents in 2010. You can buy a 98 -cent stamp or can use any combination of stamps that total 98 cents or more.
It depends on the weight of the package or envelope. Letters weighing one ounce or less require a 49 cent stamp called a "forever" stamp.
You can use US postage since origin US but since int'l will take more than 1 stamp
Yes, you can ... forever ...
No, you should only use US stamps for mail posted in the US.
Postage for ordinary first-class letters was 2 cents in 1928.
The current rate is 44 cents for standard First Class Mail.
No, you use the postage of the country where you are mailing the item.
Yes, this stamp can still be used for four cents of postage. It was issued in 1991.