Colourful: TarheelBirdy wrote good info about free-ranging.
At five months, (maybe sooner) they can eat Chicken Layer pellets (or crumble, but there is less waste with pellets) with 16% protein. I would strongly urge you NOT to clip their wings when you let them free-range - even one wing. They will be particularly vulnerable to predators if you do. Plus, it won't guarantee that they won't fly away anyway. Guineas are strong flyers. Besides, they can wander away on foot if they've a mind to and are not "home trained". If you take a little time to train them, and like Tarheelbirdy wrote, let one out at a time, then they'll come back to the coop/pen at dusk to roost for the night.
I train mine to come back to the coop by letting them out all at once about an hour before dusk, supervising where they go, and herding them back into the coop. But the concept is the same as what TarheelBirdy wrote.
When hormones kick in for the guineas and/or chickens, housing them together is more than likely going to cause aggression problems. Usually a large pen and a separate coop for them to roost in is enough. Sometimes there is one guinea that just won't "live and let live" no matter what you do, and can be re-homed or "re-purposed"
Edit: Did someone already answer these questions? My scroll bar thingy is acting funny and I don't see every post for some reason. Weird. Sorry if I'm repeating others.