What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

Can you replace the question mark with the correct number?

It spends most of its day eating white, but when it’s quick enough, it gets to eat fruit and sometimes some blue things. It’s in a dark room, where the walls are blue, it runs from a ghost that roams the halls and haunts it all the time. What is it?

It is a nine-letter word.
The exact opposite of the phrase "friendly and outgoing"
It contains the word "over".
It starts will a vowel.

What is it?

An explorer goes on an exposition in the jungle. He sets up camp in the middle of the jungle. The next morning he sees something with a head and a tail, but he is not afraid. What did he see in his bag?

The day before yesterday I was 25 and the next year I will be 28. This is true only one day in a year. What day is my birthday?

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?

John was piloting a plane behind a car but was never able to overtake it. Why?

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

A gardener planted the Lemon trees in a mathematical ordered way (i.e. he planted a tree in rows).
He created a total of 19 rows of trees.

Note: There should be more than 2 trees to count as a row.

What is the minimum number of trees required by the gardener to have 19 rows of trees?