JQUERY / POST request on OnePage CO

Can anyone tell me 2 things.
1. is JQUERY fully accessible in Netsuite, in other words is it the "full fat" version or some hybrid / cut-down crazy NS "let's be non-standard for lols version"?

2. Why does my script stop as soon as I try and do $.post / $.ajax in sites.js in the OnePage Checkout BETA implementation.
before that 2nd one looks too vague here is an example of my code :

$.ajax({
    type: "POST",
    url: url,
    data: theLot,
    contentType: "text/json; charset=utf-8",
    dataType: "text",
    success: function (msg) {
        var jsonUpdatedData = msg;
    }
});
the url is valid
theLot is a correctly formed JSON object