Questions

You will get the answer in the riddle itself, if you read the riddle carefully.

The riddle says "A cowboy arrives in town on Friday." So Friday is the name of the horse on which he comes. Hence, the only possibility is he arrives on the horse friday on Tuesday, stays for 3 days and leaves on the same horse on Friday. 

UNIA - Universal Negro Improvement Association.

It is primarily in the United States, organization founded by Marcus Garvey, dedicated to racial pride, economic self-sufficiency, and the formation of an independent black nation in Africa.

Hospitality actually means, taking care of guests in the best possible way.

Organizing, providing services and looking care after guests is included in it.

It means friendly and generous treatment of guests. 

Hospitality industry includes all companies involved in providing services for guests. They provide more mental satisfaction than tangible objects.

The Mediterranean sea separates Europe from Africa.

Black surfaces are good emitters of heat. If the black surface is rough too, the emitting will be better. Shinning surfaces reflect black radiation . So if the black surface is also shining the effectiveness of emitting heat is lessened.