I would also add some other things you need to have one is the most important is the provably fair system which is a key thing, another is the customer support which must be live 24/7 and ready to provide response to customers complaints, another one is for you to be ready to announce s soon as possible if you are having issues in other not to give room for unnecessary speculations and finally your TERMS that could be misconstrued should be explained very well...
You've already mentioned the essential points needed any gambling sites another addition is the instant withdrawal no matter big or small they have to process it immediately because as far as I know the owners of gambling will check withdrawal with a large amount.
btw we should know the type of gambling sites to be launched?