Save data using AJAX and CakePHP

I've spent today researching how to save data using an ajax request in cakephp and have got now where, the documentation on the cakephp website seems a bit lacking for this particular topic.

I have several sortable lists and I need to save the position of each list item when one is sorted. I have an ajax request set up as follows that is triggered when an item is moved:

$.ajax({                    
        url: "/orders/save_column_order",
        type:"POST",                                        
        data:"data="+data
       });

and the referenced function in the controller is:

function save_column_order(){
    if($this->RequestHandler->isAjax()){

             SAVE STUFF...

        }
  }

I have the helpers etc. set up:

var $helpers = array('Html','Form','Js');
var $components = array('Session','Email','RequestHandler');

And its not working...

So my questions are:

1) What is the current url for sending an ajax request to an action in a controller? Is it simply /controller/action?

2) What else do I need to do to the controller to access the ajax data?

BONUS:

3) Is there a way to include a custom php file in the CakePHP framework that references the database settings so I can manually update my mysql database?