Also, we have just installed nesting boxes in the coop...but they still decide that they want to lay them on the floor. At this point we aren't exactly sure how many are females or males. They just lay eggs randomly, here and there. Not sure which eggs belong to who. Are they community brooders? What I mean by that...will they sit on each other's eggs?
Guineas aren't chickens and don't have the same preferences. If you want to make guinea nest boxes you should place them right at ground level as guineas are normally ground nesters just like turkeys.
Guineas are known to be communal nesters with the nests being filled by multiple hens and also sat on by multiple hens. They may lay such huge clutches that the hatch rate ends up being very poor because they can't properly cover all of the eggs. First time hens at the start of laying season often drop eggs where ever they happen to be when the urge hits them. Later in the season the eggs will be deposited in nests.