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

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

Name a key which is hardest to turn.

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.

what does this below rebus represent identXQQQQQME

Two batsman each on 94 runs. Seven runs needed to win in last 3 balls. Both make 100*. How?

John is selling fruits.
He sells grapes at $30, Dates $25, and a Wolfberry $45.
At what price does he sell fig?

PS: Logical Thinking

How is the moon similar to a dollar?

I go up and I go down.
I go up towards the beautiful sky and down toward the green ground.
I am present tense.
I am past tense too
Children love me.

Who Am I?

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

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