The centre of the third figure is empty. What digit should fit inside?

If 1+9+8=1, what is 2+8+9?

What goes up but never comes down?

What has one eye, but can’t see?

Which word is least like the others? Third, fourth, fifth, sixth, seventh, eighth, ninth?

Twice ten are six of us,

Six are but three of us,

Nine are but four of us;

What can we possibly be?

Would you know more of us?

Twelve are but six of us,

Five are but four, do you see?

What are we?

Create a number using only the digits 4,4,3,3,2,2,1 and 1. So i can only be eight digits. You have to make sure the ones are separated by one digit, the twos are separated by two digits the threes are separated with three digits and the fours are separated by four digits

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.

Find the combined weight of the Cat, Dog and Rabbit in the given picture.

I have an eye but still cannot see.

Who am I?