Ahhh, the lovely CWatkinsNash returns, welcome back...
I do recall your previous post, in fact I read it again yesterday as part of building the list of requests I posted above. It would seem that you have indeed changed your workflow, because the plugin hasn't changed very much since then...
AFAIK Goodreads haven't changed their T&C, not that I have looked recently. However since I have not once had any email indication of users misbehaving with the plugin in it's current guise, and the number of plugin users is extremely low in comparison to the number of calibre users I'm feeling more willing to open the floodgates a little with it to make the plugin more user friendly.
In terms of exactly how many calls are being done for the various scenarios you mention, I couldn't tell you without trawling through the code. Off the top of my head, linking a book is one call per book. When you add a book to a shelf and bring up that dialog, there will be one call per 200 books already on that shelf just to validate the books you are adding are not already on there. Then there will be one call per book to actually add the book to a shelf. For the upload tags as shelves functionality, there will be one call per tag (shelf) per book. So it all adds up pretty quickly.