How many words can a pen with half refill write?

I am first found in caves, now prolific online; I am a depiction, a drawing, a symbol, or sign. I will convey whichever mood you could wish; or for that matter, a fist, flask, or fish. What am I?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

Birbal was jester, counsellor, and fool to the great Moghul emperor, Akbar.
The villagers loved to talk of Birbal's wisdom and cleverness,
and the emperor loved to try to outsmart him.
One day Akbar (emperor) drew a line across the floor.
"Birbal," he ordered, "you must make this line shorter, but you cannot erase any bit of it."
Everyone present thought the emperor had finally outsmarted Birbal.
It was clearly an impossible task.
Yet within moments the emperor and everyone else present had to agree that Birbal had made the line shorter without erasing any of it.
How could this be?

Why do we preferably have round manhole covers and not square ones?

What is the word or phrase?

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

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

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

Solve below rebus puzzle?

If an earthquake is 1 point higher on the Richter Scale than another earthquake which is actually 10 times stronger, how much stronger would an earthquake be if it was just half a point higher on the Richter scale?