We generally recommend the digital versions of our QTR reflectance sensors. You can find more information describing the benefits of using this one from my post in this thread.
Aside from wires to connect and power the sensor array from the Arduino, you should be able to read the sensors using just the Arduino Uno and a USB cable for power.
You should not expect the QTR sensor to be able to accurately differentiate between colors; as I said before, the response of the sensors will be determined by the IR reflectivity of the surfaces, and it is not easy to predict what a red, blue, or green object will look like in IR (the reason they can differentiate black and white well is that black absorbs a wide spectrum of wavelengths and white reflects a wide spectrum wavelengths).
If you want to follow a solid white or black line, our QTR sensors are a good choice, but they are not appropriate for differentiating colors and are generally not good for following colored lines. For detecting colors, you might consider something like the ColorPAL.
-Brandon