You t2t_homepage_slide($slide,$size)
function requires 2 arguments and your only calling it with one.
Either include the $size argument when calling the function or remove the requirement or provide a default when defining the function (line 94). eg:
function t2t_homepage_slide( $slide, $size="") { <--- line 94
global $wpdb;
$image = get_option($slide);
$caption = get_option($slide.'_caption');
$price = get_option($slide.'_price');
$url = get_option($slide.'_url');
Also since this is a commercial theme you should be able to get the support you need from the themes support forum.