I have one more question, I use truecaller and in truecaller I have noticed an option where it says "People you may know". What is that, it shows lots of people and I have no idea how truecaller is associating them with me ?
Are these are people who have saved my phone number or these are people who are in list or phone book of my friends, I do see some people I know but most of them are unknown person.

That wonders me too, I am not sure it if is something as you said, but most probably it is taking from list of friends phonebook as well as people saved you in their phonebook.