Can we only bet on Bitcoin or can you also add more cryptocurrency or you would just stick with one currency? I do like BNB and Dogecoin by the way I think Dogecoin could be a good idea on your website not just because the fee is low but it was commonly used in online crypto gambling.
I am confident more of the top cryptocurrencies will be added. Mainly the ones with a lot of volume of trade. I couldn't tell you exactly when but stay tuned.
Deposit bonus is a good idea but the problem is it might be abused since you can easily create multiple accounts I think it can only be applicable to casinos and sports betting websites but probably they could have at least a trading competition on which users can have more wins something, they have existing leaderboard and maybe they can give rewards weekly to top 10 players and restart the leaderboard weekly or have an option to look monthly leaderboard, weekly and competition leaderboard.
Would love to give some deposit bonus but it is quite easily exploitable as you have mentionned as you can create accounts very easily since we have no KYC. I might add one for bitcointalk users that will give them back a certain $ amount for every X amount they bet but I prefer the idea of giving rewards according to a leaderboard (either top profit earners or top wagered traders). That is the one we have planned first for 500xbit.com to favour active traders. For now, you can stay tuned for giveaways/contests specifically designed for bitcointalk.org users like this one :
https://bitcointalk.org/index.php?topic=5363672.0 