It depends upon who he provides the merchandise to. If he sells merchandise to consumers, he is called a retailer. If he sells merchandise to a retailer, he is called a wholesaler. If he distributes the merchandise to wholesalers, he is called a distributor. If he manufactures the merchandise and distributes it through distributors, he is called a manufacturer.

Different retailers handle damaged merchandise on the selves differently. Some may return it to the manufacturer and others may throw it out and writ it off in taxes.

A wholesaler marks up their merchandise or services to a retail price. They are the second level after the manufacturer.

A manufacturer is someone or group of persons/enterprise/company who produce or make things.

I couldn't find specific numbers but I know it would have to be a significant amount considering they're made by a manufacturer. Only merchandise that is made in mass quantities is made by a manufacturer.