I was intrigued enough by your question to telephone the Zambia Embassy in Washington, D.C. A nice lady I spoke to there corrected my pronunciation of the name (it's kah-oon-da), and then asked a few people in the office if anyone knew whether the name had any meaning. Unfortunately, no one knew.
The woman I spoke to explained that there are various tribes in Zambia with different languages, so the meaning of the name probably couldn't be easily traced. She summed it all up by saying: "We just know him as President Kaunda".
So, when it comes to ascribing a meaning to your name, Kaunda, I suggest that you take the best qualities of President Kaunda, and simply tell people that's what your name stands for. :)