What has to be broken before you can use it?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

What is more useful when it is broken?

I am a type of food that is often found in the fridge and can be white in colour. What I am?
Hint 1: I am a dairy product.
Hint 2: You can spread me on the bread.

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

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?