Short answers, pulled from the story.
Sikhism, also known as Sikhi, is an Indian religion and philosophy that originated in the Punjab region of the Indian subcontinent around the end of the 15th century. It is one of the most recently founded major religions and is followed by 25 to 30 million adherents known as Sikhs.
Sikhism developed from the teachings of Guru Nanak, who lived from 1469 to 1539 and was its first guru. Ten gurus established the religion between 1469 and 1708, ending with Guru Gobind Singh, who named the Guru Granth Sahib as the final and perpetual guru in 1708.
The five Ks are five articles of faith worn at all times by baptised Sikhs. They are kes, uncut hair, kangha, a small wooden comb, kara, a circular steel or iron bracelet, kirpan, a sword or dagger, and kacchera, a special undergarment.
The Khalsa, meaning pure and sovereign, is the collective body of fully initiated Sikhs founded by Guru Gobind Singh on Vaisakhi, the 30th of March 1699, at Anandpur Sahib. On that day he baptised the Panj Piare, the five beloved ones, who in turn baptised him.
The Guru Granth Sahib is the central scripture of Sikhism, regarded by Sikhs as the eleventh and eternally living guru. It comprises 6,000 shabads set across sixty ragas and includes hymns of seven Sikh gurus along with thirteen Hindu and two Muslim bhagats.
Two Sikh gurus were tortured and executed for refusing to convert to Islam. Guru Arjan was killed by emperor Jahangir in 1606, and Guru Tegh Bahadur was publicly beheaded in Delhi on the orders of emperor Aurangzeb in 1675. This persecution triggered the founding of the Khalsa.
Sikhism is a monotheistic and panentheistic religion that believes in one God called Waheguru, who is within everything and all-encompassing. The oneness of God is expressed by the phrase Ik Onkar, and God is described as Nirankar, shapeless, and Akal, timeless.