We require some addition features and im trying to find documentation on how to write a plugin or extend FPD to meed out needs.

Is there any resource on this topic?

Ok so i figured out i can take the FDP-JS from github.. build it and then replace the FancyProductDesigner.min.js in woocomerce. 
Are there any downsides to using this method? Is the FPD-JS different from Woocommerce paid version?