You're going to love every minute you spend with them! We have opossums & raccoons, both are nocturnal.
Raccoons will kill if they gain access to your flock. Oppossums mainly want the eggs. We put out live traps when they come around & then euthanize per state law.
We have been very successful with our 1st coop. The only change I would make is going to smaller hardware cloth- as it is, only small/young mice have managed to get in, and those the guineas kill immediately.
They will notice coyotes, bobcats etc before you do. Atleast one will always be on look out- and they will let you know that there's "stranger danger" (mine hate it everytime my dtr brings a new interest over to meet us & send out alerts. It's fun telling the suitor that obviously they don't approve of him....come to think of it, they've been right so far...

)-so adds a level of protection for your chickens.
Have you spent any time around a group of teenage girls? That's what it would be like to have all guinea hens-they'd never be quiet, constantly whining for a male to come for them. Once they've grouped into couples, the rest of the summer is reasonably quiet.
As
@R2elk said, if you get keets, you won't know what you have for a few months.
I thought I had 3 females left out there; now I scratch my head bc they are so aggressive w/each other at times that if Mama hadn't already raised a brood, she'd be top contender as a male.
I agree that they are flock birds...I don't fit with max quantities. But I do feel that there needs to be both genders for homeostasis.
I don't have chickens, just goons. But I trust what the others have said regarding separate housing. Infact, I'm preparing a new coop for this spring's incoming keets, bc Mama is so territorial about her coop that it'll be safer for the newcomers to have separate housing.