Answer 1

you use magic methods within classes. They allow you to use different operations on your class.
the __init__ magic method, for example, is called when a class is INSTANTIATED and lets you pass variables into your class (essentially, its the same as a constructor in other languages).
the __mul__ method lets you multiply an instance of the class by another object. eg.
class A:
def __mul__(self,x)
return 2*x

a = A()
print(a*7)
#outputs 14

the __repr__ method is used to represent your class as a string, when using print for example

I hope this sheds some light on the matter. If you want to see a real working example of this, check out my Vector2D code