Your credits should be equivalent to BTC and not on dollars. No matter how much the price of BTC fluctuates. It should be 100 credits = ?BTC and not on dollars.
No it should not, they are free to choose which unit to be used on their own site. There are some bitcoin sites uses non-btc unit on their game, usually poker sites use which worth in dollars. Fortunejack also uses $ in their games although players are still able to see the real balance in crypto.
wow a minimum deposit of $100 is quite high for a casino. Better lower the amount to atrract smaller players.
I think you misunderstood it, the minimum deposit is $1 = 100 credits.