A. I already have one
Well if you must use it, just have a transistor do the current switching with the arduino output pin controlling the transistor.
B. It casts omni directional light
Have you ever tried diffused leds, I use them in my 5x5x5 led cube and they can be seen from any angle, even from their bottom where the leads come out.
C. It can be PWM'd without flickering.
That should be something you can 'fix' with software, leds don't flicker on their own.