to stack the text on hover you could use the following:
Code
<style>
.t span {display: none;}
.t:hover span {display:block;position:absolute;}
</style>
<div class="t"><span>derder der der</span>text text text text text text text</div>
to achieve a tooltip that follows the cursor, it would require js.
edit#2: moving one with js:
http://jsfiddle.net/egr83n3a/edit: on a side note, jquery is a library made with js and the desired effect could be achieved with some simple js and not the bulk of the entire jquery library.
also, you're correct z-index is simply the z positioning of elements on a page.
This post was edited by Markro on Aug 23 2014 11:45pm