The maker of these coins is a good buddy, I will shoot him over this thread and see what I can find out for you.
IIRC yes there were only 10 pure silver coins. As to how they were distributed- would have to speak to LuckyBit.. I will shoot a message there way, it was many years ago and I can't remember the details exactly. I was only managing the design and production of them at the time. This was 5-6 years ago, so sorry I can't give more concrete info.
I do remember there were charity auctions too.
It's awesome there is still interest in these coins!