It has to do with spirituality, symbolism, and tradition. It symbolizes putting a part of four peoples spirit into woodcut. It is a tradition for all four people to put their spirit into it.
The Japanese woodcut prints were created by a collaboration between four people: an artist, a publisher, a printer and a block cutter.
This print is known as ukiyo-e prints. It involved the division of labor as the Printer printed with water inks, the Publisher financed, the block cutter carved blocks and the artist drew the colors.
You have all the answer
For #2
Just use the one from #345
1. gives the artwork life/ look realistic
2. gives depth to the artwork
