I have already resolved my issue, but I couldn’t find anyone with the same problem. So, I figured I would contribute to the public knowledge in case anyone had a similar issue.
I have a pet peeve about smileys in text messages. Since “emoji” seem to be pretty consistent among iPhone users, but not really among Android or feature phones, I have a preference for sending text smileys. Mostly this helps me be confident about how the recipient will see the message on the other side - they will see “:-)” instead of " " or a missing character box.
On the Fairphone, the Messaging app would replace most emoticons with a graphic, like an emoji. (I am not clear if there is a technical distinction between emoji and emoticons, so I’m mostly using them interchangeably.) I ended up not being able to configure the keyboard or the application itself to stop auto-inserting smileys.
My solution was to install a different messaging app. I believe there are dozens. Personally I like TextSecure because it is highly recommended by the crypto and open source communities. The devs, Whisper Systems, also published the highly successful Red Phone encrypted phone application. You can learn more about Text Secure and Whisper Systems at https://whispersystems.org/
Hopefully that helps! It’s more of a workaround than a fix, but it works for me. If anyone’s wondering, I’m on FP1, Android 4.2.2, and the default “Messaging” app identifies itself as 4.2.2-eng.hjunyu.1431026183.