The house edge on all third party games is set to the highest RTP. The house edge on X-Roulette is on the higher side at 5%.
Good to see the speed at which you are answering all of our queries. The house edge that you mentioned is way too high. I suggest lowering it asap since the competition offers similar games with a house edge of 1% - 2%.
Also, try to provide more in-house casino games instead of completely depending on third party operator based casino games.
There's no minimum deposit or withdrawal for Rollbit but we suggest ensuring the transaction is more than the network fee.
Good stuff, but I advise adding alternate cryptocurrencies like LTC, Doge, XRP etc due to the long TX times and high fees associated with BTC and ETH at present(Above posters mentioned the same).