Good Riddles

Question: I am something, a lot of people don't like me, including you,but I'm called upon anytime one is injured. I like playing with pregnant women, I'm a 5 letter word, and if my last letter is put before first letter, I become a name of a country, WHAT AM I? IF U GET THIS, U'RE INDEED A GENIUS.

Question: I am a digit, but two of the ten.
Two of me make a promise.

What am I?

Question: How many people do you need to have the odds be in favor (at least 50% chance) of two people having the same birthday?

Question: When you fall in me your as happy as could be, but you fall into depression when you lose me.

What am I?

Question: Why does the second shape have an open block when the first shape does not?