Yes. Black Friday is not a holiday.
no.
In the US, the day after Thanksgiving is not a federal holiday, so the mail will still be delivered.
YES
In Poland there is ;)
yes
Yes.
yes
Yes , the USPS delivers mail on Friday : 11/29/2013 .
Yes, it is not an official holiday.
Yes there is.
yes none tuesday-merry christmas
Yes, it is not an official holiday.