Reports are tracked separately for the various Amazon sites. You will find yourself hitting this page very frequently as the numbers pile up!
The biggest benefit of giving books away free is the exposure you receive. People who have never heard of you before are willing to take a chance at investing the one second it takes to take a peek and click. Even better, you will be aggregated with other books that are currently being downloaded by those people.
In my case, another book of the exact same Bible Character was being promoted at the same time. What a stroke of luck.
Even better - Amazon maintains separate charts between Free and Paid books, and these are updated every hour. And since the displays are arranged side-by-side, your book, if you hit the top of the chart, will be placed alongside the top Paid books, which are likely to be very popular.
Here I am at the top of the Family Saga charts right next to the PAID bestsellers "Top 100 Paid" and next to the "Hot New Releases" and the "Top Rated":
Translation to Paid:
When you go off Free, you are still associated with your cohorts. So if they continue to do well, so might you. One of the things I did was to ask my tweet team at WorldLiteraryCafe to tweet the both books on Queen Michal.
3 days later, Michal's Window ranked above #750 with 251 sold, 37 borrowed.