Short answers, pulled from the story.
Hiromasa Yonebayashi is a Japanese animator and director born in 1973 in Awata, Nonoichi Town, Ishikawa Prefecture. He worked at Studio Ghibli for 18 years before co-founding Studio Ponoc in 2015. He directed The Secret World of Arrietty, When Marnie Was There, and Mary and the Witch's Flower.
Yonebayashi's directorial debut was The Secret World of Arrietty, released in 2010. At age 37, he became the youngest director to helm a theatrical feature at Studio Ghibli. Hayao Miyazaki chose him to direct the film because the story drew on ideas Miyazaki had conceived in his own youth.
Yes. When Marnie Was There, Yonebayashi's second feature as director, was nominated for the Academy Award for Best Animated Feature at the 88th Academy Awards in 2015.
Yonebayashi left Studio Ghibli in December 2014 after 18 years at the studio. He departed alongside producer Yoshiaki Nishimura, who subsequently founded Studio Ponoc in April 2015 to produce Yonebayashi's next film.
The claim, promoted by producer Toshio Suzuki, began when Hayao Miyazaki watched a stretch of No-Face animation drawn by Yonebayashi and joked, "Isn't that Maro?" using Yonebayashi's nickname. Yonebayashi himself clarified that this quip, rather than any deliberate design decision, is the origin of the rumor.
Yonebayashi studied commercial design at the Kanazawa College of Art in Ishikawa Prefecture. Before attending, he was on a science and mathematics track at Kanazawa Izumigaoka High School, but switched to art during his third year.