Re Question 1:
[wpdm_tree download_link=1] causes this: Fatal error: Call to undefined function wpdm_is_locked() in (…)/plugins/wpdm-extended-shortcodes/wpdm-extended-shortcodes.php on line 455
Re Question 3:
Which file do I need to modify to change [wpdm_package id="5374"] colour or font size?