The more of this there is, the less you see. What is it?

Decode below three cipher riddles:

26 L of the A
7 D of the W
1000 Y in a M

P is the father of Q and S is the son of R. T is the brother of P and has a daughter U. If R is the sister of P, then what is the relation between U, Q and S?

A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396.

What is the sum of the three digits?

What two things can you never eat for breakfast?

What is black when you buy it, red when you use it, and gray when you throw it away?

A mules travels the same distance daily.
I noticed that two of his legs travels 10km and the remaining two travels 12km.
Obviously two mules legs cannot be a 2km ahead of the other 2.

The mules is perfectly normal. So how come this be true ?

Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?

What does this Rebus Picture mean?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?