What do you answer even though it never asks you questions?

Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

A patient was diagnosed with some ailment. He was given five different tablets to take at night at an interval of 15 minutes.

How long will it take the patient to consume all the five tablets?

Living above a star, I do not burn
Eleven friends and they do not turn
I can just be visited in a sequence, not once or repeatedly
PQRS are my initials
Can you tell my name accurately?

There is something which is always coming but never arrives?

It belongs to you, but other people use it more than you do. What is it?

Which of the following words don't belong in the group and why?
CORSET, COSTER, SECTOR, ESCORT, COURTS

What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

I am the first thing you need while camping.
I am always with the person named Marcos Valencia and Carrick.
But Pogba Zlatan and Rooney think I am wasteful and do not need me.
I am the second to the last thing to add when you are making a patch.

What am I?

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?