Decode below three cipher riddles:

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

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

Find the value of "?" in the ball picture Riddle below:

What happened when the wheel was invented?

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.

In one of the popular batman series movie "Batman Forever", there was a riddle that goes like "Tear me off and then scratch my head and I was red then and now I am back. Who am I?

Find the 8 in the below-given Image.

What will you call your mother's brother's brother-in-law?

What has no start, end, or centre?