I have been developing for Android for a while now and recently got interested in developing for kindle devices as well. I am not completely sure how to go about this but what I would really like to know is if it is possible to build an app targeting Kindle that will also run on all Android devices?
While the look and feel of the Kindle Fire tablet appears distinctly different from other mobile operating systems, it is actually Android in disguise. In fact, it is very compatible for existing Android applications, which is customized to remove native access to the Google app ecosystem.
The first gen Kindle Fire device is based on Android Gingerbread (API level 10), the second gen Kindle Fire devices are based on Android Ice Cream Sandwich (API level 15) and the third gen Kindle Fire devices are based on Android Jelly Bean (API level 17). See Device and Feauture Specifications at the Amazon Developer website.
For developers, this implies that building applications targeting Amazon’s Kindle Fire is similar to building an Android application. In fact, per Amazon, most of the Android applications (76% of the applications they tested) can work on Kindle Fire without needing any change or development effort.
Changes will be required when it comes to In-App-Purchase and Push Notification (Amazon provides a proprietary API for these services, Push is supported for Kindle Fire 2nd gen or newer). So eventually you might want to maintain at least two APK builds, one for Google Play and one for Amazon.
For complete steps see - setting-up-your-development-environment.