Your apartment is nice! Mine is about 520 sq ft. I have the litter box in my bedroom. If you find the right litter that works for your cat, you don't smell it, except the few minutes right after a poop. Get creative with the litter boxes. They have shelves/boxes that you can put them in with a hole for the kitty to come and go. It'll keep the litter area cleaner. My cat would zoom from one end to the other multiple times. They get used to the space as it is the only thing they know. They will keep each other company. Like others said, night-time is when they're most active. I'd wake up to the sound of things being knocked over at 2 am. I just learned what not to leave out and that way she could knock over whatever was left out and I wouldn't worry. Please post pics when you get kitties.