Hello, you will need to change some settings on your Kindle to install Firefox: 1. Go to the Settings screen on the Kindle Fire 2. Select the “Device” option. 3. Select “On” for the “Allow Installation of Applications” option.

You can then download the .apk install file for Firefox directly from https://wiki.mozilla.org/Mobile/Platforms/Android For devices without access to the Play Store, generally the Firefox Aurora version is recommended because it auto-updates...

I'm not sure about the availability of the Flash player, since Adobe has announced years ago that it was going to stop further development of Flash on mobile platforms: http://blogs.adobe.com/conversations/2011/11/flash-focus.html

Mozilla have tried to have Firefox on the Amazon App store since these devices do not have Google Play. It was there briefly for Firefox 9.0 until it was discovered that Amazon modifies and resigns the package and caused problems with updates as a result also and it was removed.

Bug 713777 is one to read to see the progress of trying to get Amazon to work with Mozilla on getting Firefox on appstore again.