Basic object oriented implementation in python

Hello I am learning python and I have this working code but in most of Object Oriented examples of python, I see people use extra stuff and I am not sure why do we need those.

I will try to explain my question with comments in the code.

class Node:

    data = none
    next = none

# Question1: Why do we have these variables outside of 
# __init__ fucntion? what are their applications? 

    def __init__(self, val):
        self.data = val
        self.next = None
    def display(self):
        next = self
        while next.next:
            print next.data, "->",
            next = next.next
        print next.data

# Question2: Do we need getter setter functions to access 
# the attributes above? I was able to remove a node with 
# simple function and it worked well

def denode(node):
    node.next = node.next.next


# Question 3: for many implementation samples of a linked
# list or something that uses Node, I see that example
# uses another class, but in the example below I was able
# to create a linked list without any trouble. why do we 
# need a separate class to create a linked list?


#ex
node1 = Node(123)
node2 = Node(134)
node3 = Node(139)
node4 = Node(148)
node1.next=node2
node2.next= node3
node1.display()
denode(node1)
node1.display()