depending fields dropdowns and checkboxes

Need a little help on this!
Meanwhile, I successfully wrote some routines using ajax and jQuery and with that, I am able to react on events like changing a GF dropdown field. Also, I found this one: http://www.gravityhelp.com/documentation/page/CSS_Targeting_Samples which helped a lot addressing GF fields.
But now I am in doubt what has to happen next. When I 'override' GF fields using jquery - let's say checkboxes - do I need to modify the $form or $entry objects as well to get correct data on submission by the user? Or in other words: what is submitted with the form? The actual (modified) content of the HTML/CSS elements or the contents of the $entry/$form objects?

EDIT: Sorry for posting early! I was wrong!
If I address the elements correctly, I get the right values! I should have taken jQuery('#choice_16_2').val instead of jQuery('.gchoice_16_2').val. With #choice_16_2 everything is as expected and fine! Forget about the rest of the post!!

Sorry but no! My current experience is different. Looking at the $entry object using a 'gform_after_submission' hook, I am getting 'wrong' values, i.e. the labels of checkboxes and their attached values are not submitting in the $entry object, although they have been changed by jQuery and displayed correctly in the form. Using Firebug, one can see the values and labels change in the HTML. On submission, I get the original label and value content as entered in the form editor ( equals the content of the $form object) . This is what I am doing:
in the jQuery part:

jQuery("#input_26_2").change(function() { //start function when dropdown changes
	var sel=jQuery("#input_26_2 :selected").val();
		jQuery.ajax({
			type: "post",url: "/wp-admin/admin-ajax.php",dataType: "JSON", data: { action: 'randomcol2', _ajax_nonce: '<?php echo $nonce; ?>', avalue: sel},
			beforeSend: function() {jQuery("#loading2").fadeIn('fast');}, //fadeIn loading just when changed
			success: function(html){ //so, if data is retrieved, store it in html
				jQuery("#loading2").fadeOut('fast');
				jQuery("#colour4").val(html[0]['value']); //fadeIn the html inside helloworld div
				jQuery("#input_26_15").val(html);
//				var result = html.split('~');
				var result = html;
				jQuery('label[for="choice_16_1"]').html(result[0]['text']);
				jQuery('.gchoice_16_1').val(result[0]['value']);
				jQuery('label[for="choice_16_2"]').html(result[1]['text']);
				jQuery('.gchoice_16_2').val(result[1]['value']);
				jQuery('label[for="choice_16_3"]').html(result[2]['text']);
				jQuery('.gchoice_16_3').val(result[2]['value']);
				jQuery("#helloworld").fadeIn("fast"); //animation
			},
		}); //close jQuery.ajax

and in the php part:

function randomcol2() {
	check_ajax_referer( "helloworld" );
	$mapid = get_map_name($_REQUEST['avalue']);
	$mapimg = get_images($mapid);
    foreach($mapimg as $image) {
            $image_deets = wp_get_attachment_image_src($image->ID);
            $choices[] = array('text' => "<div style=\"width:250 px; font-size:80%; text-align:center;\"><img src=\"{$image_deets[0]}\" alt=\"\" width=\"250\" height=\"163\" style=\"padding-bottom:0.5em;\"/><br/>".$image->post_title."</div>", 'value' => $image->ID);
        }
	echo json_encode($choices);
//    echo implode('~',$choices);
	die();
}
add_action( 'wp_ajax_' . $_REQUEST['action'], $_REQUEST['action'], 1 );
add_action( 'wp_ajax_nopriv_' . $_REQUEST['action'], $_REQUEST['action'], 1 );

And how about your German? Here is your link: http://5.9.51.145/2012/noch-ein-test/
When you click on the link with the tools icon you will get the form in a popup. Just change the dropdown selection to see the effect.
Maybe, I should give a try to what Eugene Oprea said in this post: http://www.gravityhelp.com/forums/topic/pre-rendered-checkboxes-wont-submit#post-74971

Thanks Chris,
everything is in perfect working order now.
I have a couple of forms here where this method might be very helpful. If I only were better in programming, I would consider making an add-on plugin of it. If I can trust my search engines, this is a quite common problem for form designers and 'conditional logic' helps a lot but does not solve dynamic run time probs.
Thanks again for helping!

I have solved it now with jQuery and AJAX. My plugin is close to the last step before release now, just one little issue to overcome:
in order to feed back the 'filtered' information via AJAX straigt to the DOM elements, I intended to use 'inside' functions of gravity forms like GFFormdisplay::get_field() or GFFormdisplay::get_field_content(). Thus I would be able to use a GF standard field object for filtering and feed back proper HTML code.
Unfortunately, this has one hook: those functions use the constant IS_ADMIN for modifying some elements ids and classes of i.e. input fields. In case IS_ADMIN is TRUE you get "#input_3", if IS_ADMIN is FALSE you get "#input_20_3" - the first one without form-id the second one including it. The proper one in my case would be the latter one. But I can't get it returned by the function using an ajax request via admin-ajax.php because is_admin() is always set TRUE during handling of ajax requests by admin-ajax.php. For testing purposes, I have modified the definition of IS_ADMIN in gravityforms.php like this:

define("IS_ADMIN", (is_admin() && !DOING_AJAX));

This would solve the problem!
Do I have a chance to get this modified in a next release of GF?
Or is there any other workaround to get IS_ADMIN modified just for one function call to GFFormdisplay::get_field_content() or GFFormdisplay::get_field() during an ajax request?