However many you plan on having there, expect at least half to be killed off/ die the first season. Call back cages are the way to go, with automatic feeders and waterers on timers so you never have to go around them from the first couple days on. After X amount of days, the door will open and allow them to go and come as they please, and shortly thereafter, they'll never need to come back in the cage. The biggest thing is making sure that you have NO contact with them, you want them to be afraid of you (aka predators in general).
I live in Virginia and know someone who released Chukars on their land for dog trials 7 years ago, and just saw some on his property still a couple weeks ago, so theydefinitely established themselves there.
Im not sure how releasing the pheasants are, but I'm sure it can be done in a similar fashion. Bobwhites work great for call back cages and can establish themselves really well.