DB Heroes doesn't follow the manga exactly. It takes inspiration and builds on it, making changes to suit the specific requirements of the series. However, the core elements are still recognizable.
Vegeta is also very likely to be a hero in the new story. He has grown a lot throughout the Dragon Ball series and in DB Legends, he might play a crucial role in fighting new threats. His Saiyan pride and his determination to surpass Goku could drive the story forward in interesting ways.
The length of DB mangas differs. It depends on factors like the story's complexity and the author's vision. Some might run for just a few volumes, while others could have dozens.
In the 44th episode of the TV series, He Futang decided to surrender with a gun and Fenglei Town was liberated. Ten years later, He Futang became a teacher in the school and spent the rest of his life in peace. This episode also showed that He Futang had saved Wei Zhengxian's wife, Cheng Lixue, from the strife of many forces. Wei Zhengxian decided to raze Qingmuchuan to the ground, but He Futang resolutely defected to the People's Liberation Army and ushered in the peaceful liberation of Qingmuchuan.