How can I use Greasemonkey to get information from an other AJAX site?

Question

I want to use Greasemonkey to display more information at the site menu. the new information should show how many orders/items are behind the menuelinks.

e.g. New Orders (1) Proofed Orders (20)

I tried this code:

//NEW
var pageInhalt = getTheImportant('http://example.com/orders.php?s=NEW&');
if (pageInhalt.indexOf('from ') > 0) {
   var amount = pageInhalt.substring( pageInhalt.indexOf('from ')+4,  pageInhalt.indexOf('</td>', pageInhalt.indexOf('from ')+5));
   $( "#div01" ).find( "li:contains('NEW')" ).append(' (' + amount + ') ');
}
else { $( "#div01" ).find( "li:contains('NEW')" ).append(' (0) '); }

function getTheImportant(url) {
  var result;

  $.ajax({
      type:    "GET",
      url:     url,
      async:   false,
      success: function(data) {
        result = data;
      }
  });

  return result;
}

But now the source has changed from a static table to a dynamic table. My problem is that the dynamic part will load the information I need - the amount of orders/items.

so my $.ajax isn't working anymore.

I know that I can use waitForKeyElements and I also use this succsessfull with an other script but without $.ajax call.
How can I tell $.ajax to wait for a key element?

---

Rolled in from OP's response, below:

The site with the table is behind a login. But I can show an example which looks similar:
          datatables.net/examples/styling/jqueryUI.html

There you can see 'Showing 31 to 40 of 57 entries'.
The number 57 would be the information I need.

One this page with the table I use Greasemonkey in this way:

function makeAction (jNode) {
   //find the number of entries an do somthing with the result
   $(this).find....
}

waitForKeyElements (".odd", makeAction);

But I need a little bit help how I can get this information by a link (the menuelink) using AJAX.
If I use AJAX I will get only the source code without the dynamic part - the Table. So my conclusion was I should use waitForKeyElements with AJAX?