The easiest (and for veteran teams, cheapest) way to get NeoPixels on your robot is to use an old regulator to power your LEDs and use the 5V bus from the RoboRIO to power your microcontroller.
Last year the Platypi used a Teensy and the i2c library to change the color of the LEDs based upon alliance color and game mode.
Video of the robot in action:
https://www.youtube.com/watch?time_c...&v=HAiH8s1UKus