First things first, you need to make the bloody hulk actually secure. That would mean clearing it out, deck by deck. It is recommended however that you leave some of the lower decks partially cleared, and completely separate from the rest of the hulk. This will serve as your Exotic Zoo zone, so long as you have the manpower that wont piss their pants at the sight of a chained genestealer.
After clearing the hulk, you now have the monumental task of furnishing your casino. So secure, posh, and enough counter-cheating methods to make Eldrad cautious. That means cameras, armored servitors, employed psykers, hell Assassinorum people if you can afford it.
There's also the concern of chain of supplies, a casino will consume a shiton of tabac, wine, women, and high-class goods. And you will need a steady and secure trade source to get this. Recommend having multiple suppliers.
Then comes the personnel. They will have to be loyal to the bone to you and the casino only. Recommend raising hive children into personnel. Can be trained, will have familial loyalty, and cheaper to maintain in the long run. It doesnt hurt to have an executioner killing any sorry sod that cheats you of course. They would have to be trained in both human and xeno communications, if what op wants is a galactic casino.
This includes the girls. You must have good stock of every female and male creature you can get your hands on. They will have to be able to please a myriad variety of hosts.