Whether or not the turkeys will be able to be cooped with your chickens depends on the size of the coop. Turkeys are BIG, even compared to big chickens. I've kept my 'table' birds on pasture, with no ill effect from them being allowed to walk around. They enjoy eating bugs and green plants, so it's a good thing to allow them access to pasture. Heritage birds can fly, and enjoy doing it, so it's difficult to keep them from exploring beyond the area you want them in. They enjoy roosting in high places, like tree branches and the top of your coop. I've had less success long term in keeping heritage birds on pasture, because they tend to be lured away by the local wild turkeys. If there are no tempting wild turkeys nearby, you shouldn't have that problem, but might find they'd rather sleep in a tree than in the security of a coop.
Generally, turkeys and chickens eat the same things. Turkey feed is higher in protein, which is less of an issue if you're not trying to build muscle quickly. As long as the turkeys have the higher protein food when they're young and building bone, you should be able to switch them to lower protein layer feed as adults.
There is a disease called blackhead that turkeys can catch from chickens, though it is transferred by a soil borne worm that spends part of its life in the chickens intestines. This is a big problem in some areas of the country, but is less so here in PA.
Diane W
