New to this..Can you keep guinea fowl and chickens together?

I raise both guineas and chickens. Breeding, hatching, selling, etc. Guineas do great in a coop setting, so long as they can go outside and do their own thing. They do get territorial about their own kind and "their" goodies. The most the guineas do is grab the tail feathers on the hens. The chickens keep their distance. There's a keen sense of respect through the coop and I don't worry about them at all except for rainy days when they don't want to go outside. These days they are especially crabby and picky. Lol

Guineas are roughly the size of a medium-large hen. Certainly smaller than a full grown standard rooster. They do lay in the nesting boxes alongside the hens sometimes, but we do find clutches of eggs too in hiding spots outside.

As for chick and keet rearing, we rear them together on non medicated (standard here) chick starter. Switch to grower, then once they're feathered and have healthy weight/size they go outside to the adult coop, regardless of age and put on regular layer mix. Nothing special for guineas.

ETA:

Guineas tend to be nicer to the chickens if they've been around them early in life. I only introduced 2 adult guineas, ever. Both of which were pretty bad. Very aggressive. Now we only start with our own keets or breeder stock. I also suggest starting with 18 week or younger stock to adapt to chickens. Guineas tend to stay in their own clique anyway, but just so they get desensitized.