Welcome to the world of greyhounds! It sounds like you already have the kitty litter lesson down!
We use babygates all over our house, people who visit think we are crazy, but we literally have 3 babygates within sight the minute you walk in the door. The cats have their own room where no hounds are allowed, this has their food and their beds/toys/etc and we have the litterboxes in the closet under our stairs, the door has a "cat door" in it so only the kitties can get in, no hounds allowed!
Other than that, it sounds like you are doing your research, welcome to GT and I know you will love your hound and become just as addicted as we all are!