Well this cat isn't afraid of my golden retriever when he comes charging at it! But yes the babies will be grown in my house till they are 8 weeks I think, depending how fast they grow,hahahaha! Its funny about your bird laying eggs off the roost cause one of my olive eggers is now dropping them off the roost too, cracks it good every time! How big are your nest boxes for the giants? I use milk crates for nest boxes now, but doubt they will be able to use them!
2 words for the cat problem, HOSE PIPE if you see him prowling around stalking your chickens (or golden retriever) spray em with ice cold water, he'll soon learn it's not worth it haha.