How to turn off " " surrounding vars in the output of t()?
There is actually an excellent comment in the documentation for this. Pasting here for completeness



There are three styles of placeholders:

!variable, which indicates that the text should be inserted as-is. This is useful for inserting variables into things like e-mail.

$message = t("If you don't want to receive such e-mails, you can change your settings at !url.", array('!url' =&gt; l(t('My account'), "user/$account-&gt;uid")));


@variable, which indicates that the text should be run through check_plain, to escape HTML characters. Use this for any output that's displayed within a Drupal page.

$title = t("@name's blog", array('@name' =&gt; $account-&gt;name));


%variable, which indicates that the string should be HTML escaped and highlighted with theme_placeholder() which shows up by default as emphasized.

$message = t('%name-from sent %name-to an e-mail.', array('%name-from' =&gt; $user-&gt;name, '%name-to' =&gt; $account-&gt;name));