Does rooting Kindle Fire disable your default Kindle Fire functionality?
The Kindle Fire will function as it normally would, but you cannot use the Video on Demand service while you are rooted.
The Amazon Appstore functions fine even if you're rooted.
You can revert to the "original functionality" with the "Unroot" button provided by SuperOneClick.
Nobody knows this but Amazon.
Honeycomb was not open-sourced when the Fire was being developed, and Amazon forked the Android open source code to create the Kindle Fire's codebase. Thus, the Fire was built using the newest available source at the time of development - Gingerbread.


I rooted my Kindle Fire ~30 minutes after I got it, largely because I wanted access to the Market but also to ease any development I do with it. Everything works like normal except VOD (as noted above).