They are a collection of tributes to righteous thoughts and actions, guidance on how one should behave, the virtues of being a good person etc. Take a look for yourself: http://www.srigranth.org/
They explain 'dharma', that we should fulfill our duties and engage in righteous action. Apart from that they discuss the questions about our existence and the existence of Gods. It is not necessary that they arrive at the same answer. So, there are many philosophies in India. The people are free to believe in whatever they consider as truth. Hinduism does not shackle us with a single belief.
Initially, the Scripture was called "Adi Granth"
However, now, it is called "Sri Guru Granth Sahib Ji" or "Guru Granth Sahib"
What is the holy writings for Sikhism
The Guru Granth Sahib.
Gurdwara
The two sacred writings of India are Vedas and puranas.
The sacred building of Sikhism is where the Guru Granth Sahib is kept it is also a place of worship it is called the Gurdwara which means the Gateway to the Guru
Guru Granth Sahib.
Sikhism has a sacred test known as the 'Guru Granth Sahib Ji'
A Sikh temple is called a Gurdwara.
The sacred book of Sikhism is called the Guru Granth Sahib, not Tohra.
Guru Granth Sahib is the sacred scripture of Sikhism. It is considered the eternal Guru and contains teachings and hymns of Sikh Gurus and other saints.
There is not enough room to write a summary of all sacred writings. I suggest you try a search engine for sites devoted to each sacred writing.
It is not sacred to the Sikhs. You are mixing up Sikhism with Hinduism.
The bible!
The Bible.