I activated it, but I just wondered if we got anything from those prime deals. If you enable lending on any title (select or otherwise), do they just give it free to their prime customers? How do they figure your "cut"?
There is a pool of money designated monthly. The total number of KOLL (Kindle Owners Lending Library) downloads is divided between all the authors who had titles downloaded. Example: If 300,000 KOLL downloads were made in March and the pool was $600,000, each author would receive $2.00 per download. If your e-book has 20 downloads, you would receive $40 ($2.00 X 20).
The amount in the pool is designated on a monthly basis and the royalty depends on how many titles are downloaded. If I recall correctly, last December the amount was $1.70 per title; last January it was $1.60 per title and last February it was $1.80 per title. Amazon KDP announces the amount for the previous month around the 15th (i.e., we'll find out what the amount per title is for March around April 15th).
A title that normally sells for $.99 cents will receive a higher royalty since titles priced $2.98 or less only receive a 35% royalty. Titles priced between $2.99-$9.99, will see a reduced royalty (albeit not a huge reduction if your title is priced at $2.99, much more if it is priced at $3.99 or higher).
Prime members may download one free book per month from all the books that are in the KOLL program.
ETA: I would also suggest that before you sign up for a program, read the Terms of Service. Most of your questions would have been answered by reading through the FAQ and researching the program before signing up. That's not a slam against you, just sayin' that whenever we make a contract with a person or company, we need to fully understand what it is we're signing up for.