Just trying my hands at your plugin - wow! good work!
I was a little surprised however that there's only one Author field per reference entry. My first reference was an article with two authors and that makes either the table of bibliography or the inline citation look wrong e.g using the Chicago citation style, I have "SMITH, A and JOHN, R 2012" for the author which renders as "(SMITH, A and JOHN, R, 2012)". I should think optional field for a second and third author and an et al option would be a good addition.
Are the paraphrasing citation handled in any way e.g
Smith and John have argued that blah blah blah (2012)?
I managed to create a duplicate entry for my first reference - how do I delete it except in the database?