Hi Rica, First of all, thank you for adopting some cats and giving them a loving home. I really don’t think you will have too many problems, since you said the boys were from good homes and good temperament. However, I would take the same precautions with any cat new to an unfamilar home situation. I would most definitely keep them separated for the night and probably the next day or so and introduce them very slowly to each other. The thing is to go slow and not let anyone get hurt. You did not say if the cats were declawed or not. This is something you must be careful of too, when introducing them to each other. I would do the intros by using a cat crate/carrier with the wire front. Put one boy inside it and set it in a quiet room. Let the other boy sniff around the cage. They can smell and see each other and cannot hurt each other. Then, switch them out. There may be some spitting and hissing but that is very normal. Depending on how they get on, you will know when it is safe to put them both out together. The litter box issue. Most cats (I know mine all do) prefer one box to pee in and one to do the other in. I would get at least two litter boxes and a third one if you can. They are really not that expensive anymore. While your boys are adjusting to their new home, contain them (separately) in a bathroom or small area, especially at night, with their litter box and their food and water bowl. They will quickly catch on where you want them to do their business. After the initial training, you can move the boxes if you want to…to suit you better. They will find them, trust me. You did not ask about litter, but "Tidy Cat (non-clumping)" is good and so is the "Pine Litter" and "Best Cat Litter in the World. " Hope this helps. Let us know how your furbabies get on okay?