You have struck upon the basis for Einstein's famous "Special Relativity" theory: Your perspective and position determine how you perceive the motion of other objects.
if you look at earth straight down at the North Pole, it appears to be spinning counter clockwise.
if you look a earth straight down from the South Pole (notice it is 'down' in both cases) it appears to be spinning clockwise
If you look at the earth from a point above the equator with the North Pole to your left and the South Pole to your right, the earth appears to be spinning bottom to top
If you look at the earth from a point above the equator with the North Pole to your right and the South Pole to your left, the earth appears to be spinning top to bottom.
What this tells you is that without first specifying how you are looking at the earth, your first question cannot be answered except with "It depends" (on your location and orientation).
This gets even more complicated when you ask "how do I figure out which is the "north" pole"? Astronomers use what is called "the Right Hand Rule" to determine if a rotation is "clockwise":
The north orbital pole of a celestial body is defined by the
right-hand rule: If one curves the fingers of the right hand
along the direction of orbital motion, with the thumb
extended parallel to the orbital axis, the direction the
thumb points is defined to be north
The theory is that the earth and most of the solar system's planets spin the way they do because of how they were formed out of the gas cloud that became the solar system. However Venus and Uranus spin differently. The theory is that Uranus spins "on its side" because of a collision with a very large comet or asteroid.
If the earth were to turn in the "opposite" direction of how it spins currently, a lot of things like seasons, where the sun rises and sets, the tides an all of those things would change, but the overall climate and such should stay about the same