Unless something has changed, the answers to your questions, in order are: yes, yes, no (99%), no.
I have Pyro since it is blue and my cloth is blue. It works great. I bought it before V10 was available. I see no reason to spend even more money on chalk, especially for green chalk that doesn't match my cloth. But once my Pyro runs out (in another 5 years or so) I would give it a try. With luck they'll have blue by then, or there will be another superchalk for me to try.
But if you are worried just get Pyro. It's blue, same price, very clean, and I've yet to have anyone explain adequately how V10 is really any better.