Answer 1

lets say you have a pointer that its value is an address.
but now you want to change that address.
you could, by doing pointer1 = pointer2, and pointer1 would now have the address of pointer2.
BUT! if you want a function to do that for you, and you want the result to persist after the function is done, you need do some extra work, you need a new pointer3 just to point to pointer1, and pass pointer3 to the function.

You can see on my profile an example about this.