load vs post

load vs post

I have been reading the documentation on load and post.
it seams the only differences are that

A) with load you place an element in front of it and it automatically inserts the retrieved data into that element but post does not do this so you have to write this behavior into the callback function.

B) post sends the data via POST and load does it via GET
(the get function would send it via GET but the get function does not have a parameter for sending any data to the server so in this way it is massively different from both load and post)

the documentation states that if the element in front of the load request does not exist no AJAX request is sent.

i have 4 questions

1)
am i right to believe these are the only two differences between load and post?

2)
What happens if you dont put a reference to an element in front of load?

3)
What happens if you do put a reference to an element in front of post?

4)
Since load inserts the data automatically why does it need a callback function parameter?