Can you solve the photo plexer logic ?

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.

A word I know,
Six letters contain,
Subtract just one,
And twelve is what remains.

In the below-given picture of a pretty girl, there is something wrong. Can you find out what it is?

Two girls were born to the same mother, on the same day, at the same time, in the same month and year and yet they're not twins. How can this be ?

Decode below rebus
D
N
A
T
S , D

Consider this: Arnold Schwarzenegger has a big one. Michael J. Fox has a small one. Prince doesn’t have one. The Pope has one but never uses it. Bill Clinton has one and uses it all the time. What is it?

What can you see in the middle of March and April that you can never see in any other month?

You are in a room with no metal objects except for two iron rods. Only one of them is a magnet.
How can you identify which one is a magnet?

Can you find the dog hidden in a group of pandas?