Yep, I just make whatever format the reviewer wants, and send it off.
For free promotions, you can use a site such as Smashwords, which allows you to make discount coupons, and set your discount to 100%. (Make sure your book is NOT signed up for Kindle Select if you publish electronically elsewhere, of course.) You can even make several coupons for one book, so you can tell who's used the coupons (for example, you gave group X one coupon code and group Y a different coupon code).
If you are signed up for Kindle Select, you can make your book free (but to everyone, on every site) for five days out of a 90-day period.
Reviews can be a fascinating subject that draws a lot of controversy.
On these Forums periodically you will see people offering exchange ads, which is against Amazons policy and a lot of people are against it because in a way its like I will give you a good review if you give me one.
I have seen exchange reviews offered on this forum and the people list their title and a month later you can look their book up on amazon and see where they got about 8 five star reviews within a month period. Then a week or two later people that see them and keeps track of the titles write one star reviews on the book because they are convinced that the five star reviews are fake reviews. Also I have noticed that the Five Star reviews start getting a lot of NO VOTES THAT THE REVIEWS WERE NOT HELPFUL.
People under normal conditions are lucky to get 2 reviews a year but more often only one or none.
Amazon doesn't allow us to set the price of an ebook permanently to "free" but there are a few workarounds, especially for a temporary promotion as you indicated.
If Amazon is the only distributor for your book, you can enroll your book in KDP Select. This allows all Amazon Prime members to read it without charge—however, they won't "own" a copy. When they leave Amazon Prime, they can no longer read your book without buying it. Everyone must purchase it to "own" a copy. Here's the part you'll be most interested in: When a book is enrolled in KDP Select, you are allowed to give it away for a few days for free as a temporary promotion. I think the limit is 5 days and you can divide it up as you see fit. for example, you could make it free for two different weekends (4 days) and still have a 5th free day to use another time. During these special promotion periods, your ebook is truly free. Anybody can "buy" it for free and download a copy to keep regardless whether they have an Amazon Prime membership or not.
You can "gift" a copy of your book to anybody at anytime. To do this, you buy the book for them. All you need is their email address for this. The caveat to this method of giveaway is that you must intially pay the full price for the gift. However, since it is your book, you will receive the commission for the sale, thereby reducing the cost in the long run.
Amazon has a backdoor way to set a price to "free" through its price matching policy. You must first set the price of your book to free somewhere else. Some authors upload their book to Smashwords and set the price to "free" there. Once the book is listed as "free" on another website, contact Amazon and provide them with the information. They will usually pricematch your ebook on Amazon to free as well. The downside to this approach is that there is no guarantee that Amazon will pricematch (it is their discretion) and the timing might lag making it impossible to arrange the free giveway for a precise start and stop time at Amazon. Personally, I do not recommend Smashwords—I'm simply reporting what others do. The reason I do not recommend them is because their ebook converter (called "Meatgrinder") is, in my opinion, vastly inferior to Amazon's KindleGen compiler and Smashwords will not provide any DRM protection for those who desire it.