For those who may be interested – the formatting of the lists can be achieved by accessing the styles.css file in the media/css folder. I applied a bold weight to the list items. The download icon can be varied by replacing the disk.png image in the media/icons folder. Still have not located the Filter keyword which appears to be PLG_EFLP_FILTER_TEXT constant.
Solved the location problem – its in the media folder – bit stupid of me. I would still like advice on how to change the formatting – also can I replace Filter with Search which I use in other areas of my site?