I was not given any options at all, for this or other promotions. No do I know if I will get paid for copies they give away for free. I suspect not.

As to getting the book for free, please do. I have something even more interesting in the works. I would love for you to read my book, get excited about Solr, get on my mailing list http://www.solr-start.com/ and pay me for my next project eventually.

The authors usually do not get rich of the books (though I did cover my tiny advance and more). The rest of the conclusions is left as an exercise for the reader.