yeppers, guineas have to be free in order to do their job. as a result, you are going to suffer casualties. they will go onto the road and cars will run some over. the usual predators will take some. If they refuse to go into a coop at night and roost in a tree instead, the owls will get some. if there is a fox in the area, the guineas will let you know.
the whites and lighter colored ones are the most vulnerable to predators.
the hens will sneak off and make a nest. A male will often be seen close by, in a tree, usually.
I once found a nest two feet off of the blacktop on our busy road.
after you have them for a while, you will learn their different voices and calls.
do not free range them until they are fully feathered. the young ones cannot handle getting wet from the morning dew or rain. they will die.