Quick questions on Qin Shi Huangdi's background and rise to King of Qin: HSC Ancient History

The future First Emperor was born in 259 BC in Handan, the capital of the state of Zhao, one of the warring states then contending for supremacy in China. His personal name was Zheng, and he is known as Ying Zheng (or, from his birthplace, Zhao Zheng). His father, Zichu, was a Qin prince living at Handan as a hostage, a common diplomatic pledge between rival states. Because Zichu was only one of many grandsons of the reigning Qin king and was stranded in enemy territory, the child born to him had, on the face of it, only a distant claim to power.

King Zhuangxiang's reign was brief. On his death, his young son succeeded as King of Qin in 246 BC, aged about thirteen (Ying Zheng was born in 259 BC). Because the new king was a boy, real power lay with the chancellor, Lu Buwei, who now served as regent and was honoured with the title Zhongfu, conventionally rendered "second father" or "uncle-father." For roughly the first decade of the reign, Qin was in practice governed by Lu Buwei and the queen dowager (the king's mother).

The Lao Ai affair fatally compromised Lu Buwei, since it was he who had originally introduced Lao Ai to the queen dowager. In 237 BC the king dismissed Lu Buwei from the chancellorship. He was first sent to his estates and then ordered into more distant exile in Shu (Sichuan); facing ruin, Lu Buwei took poison and died in 235 BC. The kingmaker who had, on the tradition's own account, manufactured the entire dynasty's fortunes was gone within a few years of the king coming of age, removed by the very ruler he had raised.