When do guineas start laying?
I know they'll nest on the floor if you put plywood (or other material) at an angle in a corner. Some will nest in tall grasses.
I have all females and they roost with the chickens, but that's because I trained them to do so. You have to train them to the coop, otherwise, they'll roost in the trees. Mine will hang out on the lower roosts during the day, but sleep in the rafters at night.
My male, who has since joined the wild turkeys in the woods, has bigger waddles and a bigger helmet than the females.
If guineas aren't socialized really well with humans, they'll be very timid. Their bite hurts too - even through leather gloves! So be careful when handling adults.