How can you make number one disappear by adding something to it?

I am a type of word that is spelt incorrectly or used differently, on purpose for humour. What am I?
Hint 1: You can find me in a joke.
Hint 2: I am a play on words.

What kind of band never plays music?

What goes up but never comes down?

If all the below statements are true

1. Gianni was either in Italy or France in 1997.
2. If Gianni did not kill Versace, Hilton must have killed him.
3. If Versace died of suffocation, then either Gianni killed him or Versace committed suicide.
4. If Gianni was in Italy in 1997, then Gianni did not kill Versace.
5. Versace died of suffocation, but he did not kill himself.

Who killed Versace and where was Gianni in 1997?

As a whole I am both
safe and secure.

Behead me and I become
a place of meeting.

Behead me again and I am
the partner of ready.

Restore me, and I become
the domain of beasts.

What am I?

Begin with a word, five letters to my name,
Remove the first and last but I am the same
Take out my middle and still, I remain.
What word am I?

Can you count the number of lines in the below picture?

Different lights make me strange by changing me into different sizes. What am I?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?