@ElizabethN - thanks for the sites, I shall take a look at home where I won't be battling against work web filters. I will say that provided an author is at Fantastic Fiction then there isn't normally any need to use an author specific site. For the authors it covers the FF site is generally very good. And it should save you the data entry you mention.
Title/author is all the data needs - in fact it is all the plugin currently allows you to extract be it from clipboard, CSV or the web. It also supports "title only" matching with the obvious downsides that will have. In theory I could add support for other metadata fields, but as this is not intended as a replacement for metadata download and would clutter the UI then title/author should be sufficient. You can let the plugin create the empty books, and then do a metadata download to get the rest of the data.
Just on your final point. If you point the plugin at a website that isn't bundled with it, then you almost certainly won't get any menaningful data from the page. Every website needs its own configuration, because every website displays different html which we scrape the data from. Just like we have different metadata download plugins for different websites.
The good news is that frequently a single website will use the same html template for all its pages - hence why a single template can cater for any author from Fantastic Fiction rather than a different one for each author for instance. Creating the configuration for a website does require some xpath knowledge so I don't anticipate every user out there diving in to do it but the ability is there for those who want to and export it. The more websites over time I bundle with this plugin the more generally useful it may be out of the box.