Yep. This is for [e]Kindles.
It's a screen reader that uses e-ink screens that save a lot of power and barely have any of that blue light that hurts your eyes.
You can manage your collection with Calibre (and at least used to auto-strip DRM in the process) without jailbreaking, I did that with the Kindle Keyboard many years ago.
The only thing I remember about jailbreaking, was being able to use custom screensavers and fonts.
I didn't have any issues removing drm from my purchased amazon books as of a few months ago using the latest version of calibre released at the time and the latest version of the kindle for windows app.
No it doesn't. You can install the Google Play Store without jail breaking.
I've installed the Play Store on 3 Fire tablets, and I've never done a jail break.