Short answers, pulled from the story.
Daulat Khan Lodi was the governor of Lahore from around 1500-1504 until 1524, serving under the last two rulers of the Lodi dynasty, Sikandar Khan and Ibrahim Lodi. He is historically significant because his invitation to Babur to invade India set in motion the events that ended the Lodi dynasty and led to the founding of the Mughal Empire after the battle of Panipat in 1526.
Daulat Khan invited Babur after his son Ghazi Khan returned from Delhi with a warning that Ibrahim Lodi was planning to remove his father's governorship. Facing the loss of his position, Daulat sent messengers to Babur in Kabul offering allegiance in exchange for military assistance against Ibrahim Lodi.
After Babur captured Lahore and Dipalpur, Babur gave Daulat Khan Jalandhar and Sultanpur rather than restoring Lahore to him. Daulat refused these assignments and went into hiding. He later surrendered at the fortress of Milwat after Babur laid siege to it, and died on the road to Bhera, where he was to have been imprisoned.
One of Daulat Khan's officials, Jai Ram, was married to Nanaki, the sister of Guru Nanak. Jai Ram arranged for Guru Nanak to work as a keeper at Daulat Khan's store and granaries. When Nanak faced accusations of wasting the stores and later of spreading religious teachings, Daulat Khan defended him; two audits confirmed the accounts were correct.
Daulat Khan's father was Tatar Khan, who had previously served as Nizam of Lahore and had at one point asserted independence from the Lodi dynasty under Bahlul Khan Lodi, the father of Sikandar Khan Lodi.
Daulat Khan had several sons who took opposing sides. Ghazi Khan Lodi first warned his father of Ibrahim Lodi's plans and later went into hiding with him at Milwat. Dilawar Khan accepted Sultanpur from Babur and was given the title Khan Khanan, effectively betraying his father. A son named Hajji joined Alam Khan's unsuccessful siege of Delhi.