Yes. Billy Russo is indeed a character in the Punisher comics. He has a significant impact on the overall narrative and the development of the Punisher's story.
Billy Russo in the Punisher comics is a villain. He has a troubled past and a deep-seated grudge against the hero. His actions drive much of the conflict in the story.
The protagonist of "Death Zone" was the American general during the Vietnam War, John F. Kennedy. During his time as president of the United States from 1963 to 1967, he led the military operation against Vietnam, which was known as the "Kennedy War." During the war, he faced many political and military challenges, including domestic and international pressure, but he insisted on taking a series of measures to support Vietnam and eventually led to victory in the Vietnam War.
In the comics, the Punisher isn't simply heartless. His actions are a result of his traumatic past and a determination to fight crime by any means necessary. It's a mix of passion and a warped sense of morality.
I don't think there was a character named Karen in Punisher comics. Usually, the main characters and well-known ones are pretty distinct, and I haven't come across a Karen in this series.