In certain comic arcs, Pietro's fate is that of death. However, comic universes are complex and his status can vary depending on the specific storyline and alternate realities.
Wanda and Pietro did not date in the comics. Their connection is that of brother and sister, and the storyline doesn't depict them in a romantic relationship.
In the comics, Wanda and Pietro did not sleep together. Their relationship was more focused on their superhero activities and family dynamics rather than anything of that nature.
Jiang Ziya died twice in the Investiture of the Gods.
The first time was related to the war at the end of the Shang Dynasty. He was killed by the son of King Wen of Zhou, King Wu Ji Fa, when he fought with the Zhou army.
The second time was after the establishment of the Zhou Dynasty, when Jiang Ziya was honored as the Grand Preceptor and became the Duke of Western Zhou. However, he was surrounded by the new emperor Zhou Qi and eventually committed suicide.