Tpl files I believe are just a fancy name... you can create your templates like the following:
Template.php
<html>
<head><title>Hey!</title></head>
<body>
<h1>Hi!</h1>
<?php
#
Code goes here
#
?>
</body>
</html>
Well that's how I've done mine anyway... I've got dynamic navigation and many scripts inside each template... works for me.
As for variables, I'm just starting to learn about them... I've got another post somewhere... something like, Links titles and more... I've asked about variables in there!
Thanks,
Chris