Guess My B'day

Source: Tanya Khovanova Blog

My birthday is in January. What is the smallest number of yes/no questions you need to ask to determine the day of my birthday.

Turtles

Source: Mathematical Circles: Russian Experience by Dmitri Fomin

Problems :Three turtles are walking in the same direction in a row .
First turtle said: there are 2 turtles behind me and no turtle in front of me.
Second said : there is one turtle behind me and one in front of me.
But the last turtle said there are 2 turtles in front of me and two behind as well.
How??

The common elevator puzzle

Source: Some puzzle Site

Problem:

A man works on the 10th floor and always takes the elevator down to the
ground level at the end of the day.
Yet every morning he only takes the elevator to the 7th floor and walks up
the stairs to the 10th floor, even when he is in a hurry. Why?