Hello, I have to add one critical thing about guineas, THEY ARE LOUD!!! If you have neighbors near by (couple of hundred feet), or like the peace and quite of country life, Think Twice About Getting Any. We had about a eight when we first got chickens. they were kind of obnoxious. They also insisted on sleeping on top of the chicken coop instead of inside. The first night on pasture (movable chicken tractor, electronet fence,) an owl got one. After that we went out at dusk and grabbed them and put them in the coop. However timing was critical, had to wait until they were roosted to grab them, but owl came earlier and earlier it seemed, so if we waited til it was dark owl would get another. Eventually only one was left, so he slept inside with the chickens after that. They are meaty, small turkey size (our dog got lucky with all the leftovers from owl just eating heads and guts.
Mother Earth News just had an article about ticks, and suggest chickens good at controlling them. Our ~dozen hens free range from ~ mid october til ~ mid april (minus when snow on the ground) We just put them in fence when we plant the garden. They roam all over the ~ acre of yard, don't roam out into our open pasture too much. Seems like we get less ticks now than used to but hard to say.
Good Luck