Can you replace the question mark with the correct number?

John is asked to stand behind Jacob and Jacob is asked to stand behind John. Both of them feel confused about it and don't know what to do?

But it is quite possible, do you know how?

What can go up a chimney down, but can’t go down a chimney up?

A man says, "Brothers and sisters, have I none, but that man's father is my father's son." Who is that man?

What famous saying does this rebus mean?

COME SERVED <---
COME SERVED
COME SERVED
COME SERVED
COME SERVED

Bopanna was working on a murder case when he received a message about the location of the murder weapon.
The message was encrypted as below.

"deb mitciv eht edisni neddih si nopaew redrum ehT"

Tell me the location of the murder weapon.

Count the number of squares in the picture below.

In a boat, the father of a sailor's son is sitting with the son of the sailor. However, the sailor is not present on the boat.

Can this even be possible?

Decode below rebus
D
N
A
T
S , D

What is the next number in this matchsticks series riddle?