I run a daycare and deal with 1 year old's being jelous and a little mean to the little babies. I do have to keep them apart as much as possible.
I actually enjoy keeping them on opposite schedules. What I do is set the times the babies will be in their beds. Once I change them and I know they are full enough, I put them in their beds with some music and shut the door. That gives me time now to pay attention to the other child that needs attention. I do my best to piggy back their rest periods all day. I will not go back into that room while they are having their rest time. Even if they cry, it will not hurt them and their rest periods get easier when they get used to being on a schedule. They learn that you are coming back.
However, the older babies don't sleep as much as the young ones, so they will be around the little baby at some point. It's at that point that I will put the older baby in a highchair with some toys or in a pack and play in the same room with the rest of us. I try hard not to look at it like they are being really mean. It can seem mean, but how much do they really understand at this age? I do tell them sternly when they are doing something they should not. I tell them it's mean too because that's how they will learn. But it can take months sometimes for them to learn.
I just had a little boy go through this. It started around 15 months. He would pick up a toy car or block and just wop one of the little ones on the head. I'd pick him up and put him in the highchair and he would play in there for at least 30 minutes to an hour. He actually liked the chair just fine so it wasn't a struggle. By the time he'd get out of the highchair, the little baby would either be napping or safely in a seat, baby swing, or pack and play, but out of reach of the little one.
I care for 4 children unrelated to me plus my own daughter. I am open 24/7, so I have many kids that come and go on various days ranging from 1 day per week to 5 days per week. It makes for some interesting dynamics.
All I can suggest about getting the house clean is turn on some great music and work fast. Clean the house in little 15 minutes spurts through out the day. You'll learn to keep up. But your bound to be feeling overwhelmed for awhile. Give yourself a break. You'll get throught his. I know it can be difficult. But just be glad it won't last forever! LOL. In my case, everytime one of them gets old enough for school I am taking another newborn into care and my last year babies are learning to walk while the year before babies are 2 and going through some very stubborn stages.
take care
Suzi