I Am Xiao Yan in Dou Po

What would happen if the person who traveled through time and became Xiao Yan was a soul who knew the plot well? Does Yao Lao really need to absorb Xiao Yan's fighting spirit to cultivate his soul? Why did Gu Yuan put four-year-old Gu Xun'er into the Xiao family? (The author promises that this is the most thoughtful work and will fill in the pitfalls of the original work reasonably!)