[Plugin: Ambrosite Next/Previous Post Link Plus] looping disabled, but links still displays

i have the following:

<?php previous_post_link_plus( array(
                         'order_by' => 'custom',
						 'meta_key' => 'begins',
                         'max_length' => 30,
						 'thumb' => 'thumbnail'
                    ) );?>

<?php next_post_link_plus( array(
                         'order_by' => 'custom',
						 'meta_key' => 'begins',
                         'max_length' => 30,
						 'thumb' => 'thumbnail'
                    ) );?>

meaning i have left looping at the default, disabled state. however, it still allows looping.

also, how can i give next and prvious links different classes, so i can apply different styling in css? for example, i may want to float one left, and the other right, etc.

thanks.

http://wordpress.org/extend/plugins/ambrosite-nextprevious-post-link-plus/