To answer your other question, I like to view it more like leghorns have the ABILITY to be flighty. I haven't found them to leave the property with no reason, or be birds that stress easily, quite the contrary actually, I feel more safe knowing that my birds can fly well and escape predator...
Omg YES I wanted to add it to the list but I completely forgot, mostly because I have no personal experience with this breed, but a breed that I believe will totally fit your needs. That breed is the Buff Orpington!
Well, first of all I would like to preface this by saying nothing is set in stone. Buying birds of any breed from good breeders will increase your odds of success drastically.
That being said, I have one breed in mind, well actually more like two
The first one, the one I will recommend, are...