Short answers, pulled from the story.
Violence Jack is a Japanese manga written and illustrated by Go Nagai, serialized from 1973 to 1990 across multiple magazines. The series spans roughly 38 tankobon volumes and is credited with introducing the post-apocalyptic genre to manga and anime.
Three Violence Jack OVAs were produced. The first, Harem Bomber, was released in June 1986; the second, Evil Town, was released on the 21st of December, 1988; and the third, Hell's Wind, was released on the 9th of November, 1990.
Violence Jack: Evil Town was refused a classification rating by the Australian Classification Board in 1997, effectively banning it. The submitted version was the already-censored UK cut running 55 minutes rather than the original 60-minute print, and the ban led to the cancellation of the remaining OVA releases in Australia.
In the final chapter of the original manga, Violence Jack is revealed to be Akira Fudo, who is one of three parts forming Devilman. The post-apocalyptic setting is a world re-created by God in which Satan, identified as Ryo Asuka, is punished. In the reboot Shin Violence Jack, Jack is instead identified as the demon Amon.
Violence Jack is cited as an influence on Mad Max, which debuted in 1979, and Fist of the North Star, which debuted in 1983. Kentaro Miura, creator of Berserk, and Goichi Suda, creator of No More Heroes, both cited Violence Jack as a direct influence. M.D. Geist and the Atlus series Digital Devil Story: Megami Tensei II are also among the influenced works.
Uncut versions were released in France in 1999 by Manga Entertainment, in Italy in 2003 by Shin Vision, and in France again in 2003 by Fox Pathe Europa. In the United States, Right Stuf released an uncut version in November 1996 under the Critical Mass label. Discotek Media released the full uncut OVA series in 2015.