You can use any years stamps to send letters and parcels. You just need to affix enough for the current rate for your shipment. The value of the stamp is always written on the stamp. If it says forever then it is worth the current rate of a 1oz first class letter.
Yes
Stamps show that you have paid the money to have the letter delivered.
Currently as of 2011, it costs 59 cents.
No they are not valid for use in the United States. You must use stamps of the country of origins when mailing something, in this case, the US.
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, you can use regular stamps on first class mail. Most letters that you would mail only take one or two stamps.
As of October 2011, Canada Post domestic lettermail costs $0.59
I successfully mail CDs all the time with 2 stamps.
Depends where you are. Some countries issue stamps for first class mail, some don't.
The person who received the mail.
how many forever stamps = .94
4 stamps