Is there a import format/filter within Bookends that can take a formatted list (such as APA 5th Ed: the reference list at the end of the journal) and split the reference up into the appropriate fields and import them into bookends?
If there isn't a standard filter, how do I set one up?
There is a section in the User Guide that tell you have one might approach creating such a filter, but there are lots of caveats and reasons why it won't work well.
Search the user guide pdf for "existing bibliography" and you'll find the section.