Short answers, pulled from the story.
A. Merritt, born Abraham Grace Merritt on the 20th of January 1884, was an American Sunday magazine editor and writer of fantastic fiction. He wrote eight complete novels and a number of short stories, including The Ship of Ishtar (1924), Burn Witch Burn! (1932), and Dwellers in the Mirage (1932), mostly published in Munsey pulp magazines.
Merritt's primary career was journalism. He served as assistant editor of The American Weekly from 1912 to 1937 under Morrill Goddard, then as its editor from 1937 until his death in 1943. By the end of his life he was earning $100,000 yearly, making him one of the best-paid journalists of his era.
Yes. Gary Gygax, co-creator of Dungeons and Dragons, listed Merritt in Appendix N of the Dungeon Masters Guide and often cited him as one of his favorite fantasy authors.
Merritt was inducted into the Science Fiction and Fantasy Hall of Fame in 1999, as part of its fourth class, which included two deceased and two living writers.
Michael Moorcock and James Cawthorn included The Ship of Ishtar and Dwellers in the Mirage in Fantasy: the 100 Best Books. Karl Edward Wagner and Robert Bloch both placed Burn Witch Burn! on their lists of the best supernatural horror novels.
Merritt died suddenly of a heart attack on the 21st of August 1943 at his winter home in Indian Rocks Beach, Florida.