When exchanging your money for bitcoin cash, you will have to pay a commission on the exchange in the amount of 0.25 USD. Therefore, it would be better to exchange a large amount at once in one transaction than a small amount in several tranches, so you can save on commissions. As for the casino, there is no commission when crediting bitcoin cash to the casino account (if the casino really supports this currency). It often happens that a player enters an unverified casino, sees that it is possible to play in it for one or another cryptocurrency, makes a deposit and surprise he has to pay a commission, which means that the casino does not actually support the game for this currency, but only accepts your deposit in the crypt and immediately converts it into fiat money, and the commission is charged to the player.