Category List With Comma & Link

You can use the_category if you are in the loop:

<?php the_category(', '); ?>

If not, then use this code:

<?php
$output="";
foreach((get_the_category()) as $category) {
    if($category->name==$homecat) continue;
    $category_id = get_cat_ID( $category->cat_name );
    $category_link = get_category_link( $category_id );

    if(!empty($output))
        $output .= ', ';
    $output .= '<span class="cat"><a href="'.$category_link.'">'.$category->cat_name.'</a></span>';
}
echo $output;
?>