Question about plugins

Good Evening

I recently started to use Tellico to manage my book collection.

I also started to use a  online  book  site  (commenting,  rating  etc),
http://www.goodreads.com

I would like to sync my tellico book list with the online collection.

I'm using a plugin to submit the info of an individual book (via "update
entry") the goodreads site.

Is there:

        + Any documentation on tellico plugins?
          (namely, how do I send back info from the plugin to tellico?)

        + Any simple way of passing the entire book  collection  to  the
          external plugin (batch sync instead of single book)?

        + Any other hints?  

thanks in advance!
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People who think they know everything greatly annoy those of us who do.
---
Jose' Carlos Pereira