The lumen output is right on the First Choice page:
http://firstchoicebyandymark.com/en/fc14-060
The distance will depend heavily on your vision code and camera settings. If you're code can reject false detections, you can open up the thresholds and your light doesn't need to be as bright. Alternately, if you turn down the brightness of the camera, you will need a brighter light, but it will minimize the number of false detections. The best thing to do is start playing with it now.
In 2012, we used only 6 LEDs (significantly less bright then the FC ring light). We could detect the vision targets from the key (12 feet away).