What does this rebus riddle means ?

Count the squares in the matchstick puzzle below?

First, think of the colour of clouds. Next think the colour of snow. Last, think of the colour of the moon. Now, what do cows drink?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

Can you decipher these quotes by Albert Einstein?
Blf xzm mvevi hloev z kilyovn lm gsv ovevo lm dsrxs rg dzh xivzgvw.

An office is divided into 8 cubicles. How many of the cubicles are painted if only 1/8 of the cubicles are painted?

What's a single-digit number with no value?

What building has the most stories?

What brings you down but never up?

What is at the end of a rainbow?