Can I download a kindle-formatted book from Amazon and then read it using the Books App on my MBP or iPhone or iPad?
You are unlikely to be able to read it in the Books app on your Mac or iOS devices, you will be better off just using the Kindle apps on your Mac and devices.
The only place to get the Kindle app is the App Store. As the current version iOS 10+, and if you don't have the app in the account's purchase history so you can try downloading a previous compatible version via the Purchased tab in the App Store app on the iPad, you/she could try just using their 'cloud reader' (go to http://read.amazon.com in Safari and save a homescreen shortcut)
I have my wife's iPad(2) with IOS 9.3.5. What Kindle app will work with this? Where can I obtain the app?
Kindle books
