I'm testing the speed of my site with Pingdom load time tester and it's suggesting that I do the following things:

Leverage browser caching

and

Specify a Vary: Accept-Enconding header

How do I do the above?

Is this possible with meta tags?

Here's my current Meta tags:

Code:
<?php
$expire_cache=strtotime("+10 days");
$expire_cache=date("D, j M Y", $expire_cache);
?>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta http-equiv="Cache-Control" content="Private" />
<meta http-equiv="Expires" content="<?php echo $expire_cache; ?> 23:59:59 GMT" />