Missing argument 2

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.