These bugs were fixed by changing the opening php-tags (<?) to (<?php) in the following files:
* wm_functions.php
* wm_dir.php
This took care of the error messages I posted above, but uploading a file now results in an error. Watermarks are not being applied, and the error message contains no information as to what’s causing it. It might be a conflict with another plugin, not sure. I’ve contacted the author of this plugin and hope to resolve it soon.