What is the ruling on kissing graves and kissing the hands and feet of shaykhs, and did the Prophet (peace be upon him) do that?

Praying at graves, kissing them, prostrating before them, and glorifying them are reprehensible and forbidden acts. This is a means to major shirk (polytheism). The Prophet (peace be upon him) forbade taking graves as mosques and praying towards them. It is also forbidden to kiss shrines and graves, as it involves submission to other than Allah and glorification of the dead.

As for kissing the hands and heads of scholars and shaykhs, there is no harm in it if it is done out of respect and reverence, as long as it does not become a habit. However, kissing the hands and feet of ignorant Sufis is not permissible. The Prophet (peace be upon him) visited his mother's grave and sought his Lord's permission to do so.