[jQuery] Migrating from prototype to jquery

[pytrade]

I have the following code which will add error messages for ajax
requests and a busy indicator at the bottom of the page. How would I
migrate this to jquery? I've migrated from lightbox to thickbox and
auto complete to auto complete, without any problem. I had one problem
where the page would not reload in ie since the script tag was writing
to the dom before the page load was completed. That was fixed by
adding a defer='true' to the script tag.

I still have the following questions:

Question 1:

Ajax.Responders.register({
        onCreate: function() {
            $('headerPageError').innerHTML = ""
            Effect.Fade('headerPageError',{duration: 0.25, queue: 'end'});
                if($('notification') && Ajax.activeRequestCount > 0)
                        Effect.Appear('notification',{duration: 0.25, queue: 
'end'});
        },
        onComplete: function() {
        if($('notification') && Ajax.activeRequestCount == 0)
                Effect.Fade('notification',{duration: 0.25, queue: 'end'});
        }
});

Question 2:

How would I do the following simple ajax request with jquery:

    new Ajax.Updater("id_of_div_content_to_update", someurl).value,
{});

Question 3:

Will the $("some_id") continue to work with jquery?