I wouldn't be trying to house them in the coop with your chickens. They're going to need their own barn.
All your fences are also going to need to come up to at least six feet tall, because they can and will jump over anything shorter. Actually, some states have certain requirements about fence heights for ratites and might require at least eight feet, maybe more. You'd want to look into that.
They're not something I'd want around children under twelve. Not because they're aggressive, per se, but because they could very easily hurt a smaller child without meaning to, by either knocking them over or running over them when they get sprinting. So if you have younger kids, that might be something to consider as well.
They do live a long time, up to 35 years or longer, as someone already said, so be sure you're ready to commit to 35 years of emus or know what you're going to do with them if you can no longer keep them at some point.
For housing, for one pair a run of 20 feet wide by 100 feet long is basically what you want as a bare minimum. They are fence pacers, so most of the space they utilize is down the fence line, and they need the vertical room to be able to run without running into the fence all the time.
And be aware that they can hurt you. They're a big animal like horses, so they can hurt you accidentally - or on purpose. This bruise is one I have that's still healing. I bought a new male this year for breeding season and he managed to find a weak point in my fence and let himself and his intended girlfriend out. While I was catching him (and that was fun, because I had to find him first - emus aren't like other poultry, they can't free range, and once they get out they just start heading off) he kicked me in the arm. He didn't even get a particularly good shot and this is the damage:
And he's not a particularly wild bird. He was raised by humans and isn't super skittish or afraid of people or anything like that. This is just what can happen.
Now, all that said, I still love my emus. I think they're great to own, as long as you can get set up for them properly and are fine with taking the risk that, at some point, they're probably going to hurt you, either accidentally or on purpose.
Ciara, my female, is a sweetheart. She will let me dress her up. She lets me pet her. She is not aggressive and is very friendly. Her presence helps deter predators for the smaller birds, too.
So they can make good pets. You just have to be very prepared for them. Think of it more like getting horses than getting new poultry.