The biggest problem with Fluorite is the assumptions made about it without doing any real research. The stuff is inert, so by itself it won't do anything for your plants. What it does is act like a sponge by soaking up any extraneous minerals/ferts available to it in your water. Then it can leech these materials back to the plants when/if the concentration available to the plants is lower than whats stored in the Fluorite. This is what is know as the CEC. Theoretically it could actually compete with your plants for the ferts until it reaches a "saturation" point and stops absorbing material.
This is the reason many people complain about it (other than the dust it contains). By itself it won't do you much besides physically anchoring your plants. You have to fertilize your tank to get the benefits of having it.
As far as turning the water white, I've been using both the original red and now the black and black sand for a while, years worth and many, many tanks and never had any issues like that with it. And for my other 2Ę...no, I don't rinse it, just fill the tank very slowly and you'll be fine with it.