You really should have done a search in the
Guinea Fowl forum. What is most likely to happen is that everything will seem to be fine right up until the guineas reach their first breeding season. At that point the guineas will begin their inherited mating rituals. Guineas have completely different behaviors and rites than do any other poultry. The guineas will likely stress the chickens out very badly.
Successful matings between guinea males and chickens are usually not successful because of how guineas mate naturally. Successful matings between guinea hens and chicken roosters can occur. In most cases these are encouraged by penning a rooster in a cage with the guinea hens.
There isn't much point other than developing a strange looking bird in making guinea/chicken hybrids since they have been said to be infertile.
Guinea keets should be fed a high protein turkey/gamebird starter which has a much higher % protein than does chick starter. Turkey/gamebird starter also contains higher percentages of lysine, methionine and niacin than does chick starter. The higher protein and other additives allow the keets with their high metabolic rates to develop properly during the early days of their lives. When I brood keets and chickens together, both the keets and chicks get a 28% protein turkey/gamebird starter, I have done this for many years and have never seen any signs that the high protein feed is harmful to the chicks.