What does an Island and the letter T have in common?

What is the riddle which can be asked all day with a different correct answer each time.

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

John is the son of Jacob.
So,
Jacob is the_____of John's father?

A man calls his dog from the opposite side of a river. The dog crosses the river without a bridge or a boat and manages to not get wet. How is this possible?

You need to move three matchsticks to form three squares. Can you do it?

I am five letter word that is under you.
If you remove my 1st letter, then I am over you.
If you remove my 1st and 2nd letters then I am all around you.

Who am I?

Cristina was born in 1888. She just had her 30th birthday today how did that happen?

Rumel, A detective who was mere days from cracking an international smuggling ring has suddenly gone missing. While inspecting his last-known location, you find a note:

710 57735 34 5508 51 7718

Currently, there are 3 suspects: Bill, John, and Todd. Can you break the detective's code and find the criminal's name?

The barber of Town shaves all men living in the town. No man living in the town is allowed to shave himself. The barber lives in that town. Who then shaves the barber of the town?