Mo is the girl, Larry is the boy. That's my story and I'm sticking with it 
They can't be in the kitchen or the bathroom unsupervised now because there are large holes where the pipes go behind the walls and they might fall in there. I've been trying to get my landlord to fix them forever but he's planning some remodeling and keeps saying we'll do it all at once. I'm supposed to get some new cabinets and counter tops out of the deal so I don't want to complain about it.
My previous concern with those holes was that an occasional mouse would get in. A couple times I found them dead in the middle of the floor after getting into a poison trap down in the basement. Now I'm worried one of the kitties might kill a mouse when they're older and possibly ingest some of that poison. I can keep the kitties out of the danger zones by keeping doors closed, but I can't be 100% sure no mice get in.
But otherwise the kitty-proofing is fairly easy. Lots of cardboard and tape 