Guru Gobind Singh is the tenth guru of Sikhs
The Guru Granth Sahib Ji is believed to be such a sacred object for Sikhs because the holy book contains precious hymns and teachings from the guru's. This is why Sikhs respect the Guru Granth sahib ji in an orderly fashioned way by going to the Gurdwara ( Sikh temple )
Sikhs DO NOT worship Guru Nanak. They worship the Divine Light of God that is in Guru Nanak. Guru Nanak is NOT a deity in the Sikh religion, he is a teacher. Sikhs still bow today to Guru Granth Sahib. That does not mean they worship it, it means they revere the Divine Knowledge that it contains.
To show respect towards the Guru Granth Sahib.
they wrap it up and place it on a heigh shelf
Because when the book is brought it is as if all 10 gurus are sitting there, like as in a court. That is why we Sikhs treat the holy book with great respect. Source: Was at a Sikh wedding the other day.
Shri Guru Granth Sahib is the holy scripture of the Sikhs, revered as the Guru of the Sikhs.
For religious Sikhs their biggest influences would be the guru's and the Guru Granth Sahib and they hold high respect for the Granthi's and the elders because they are usually wiser. For non-religious Sikhs it is usually the same as above, but they are also influenced by celebrities and TV
Guru Tegh Bahadur was the ninth Guru of the Sikhs.
Guru Granth Sahib Dev Ji is the living embodiment of Guru as well the eternal Guru of Sikhs, it contains the teachings of Sikhs Gurus as well as the teachings of Sikh Devotees.
Guru Granth Sahib Ji is the Guru of Sikhs and thus hold the highest importance for Sikhs when it comes to the matter of religion as Guru Granth Sahib Ji is the authority of the Sikhs.
Guru Nanak is the final and eternal guru of the Sikhs. He was the first of the Gurus to find the Sikh religion.