Ah man, you are asking questions that have been turned and turned again on this forum, but I will help you out. In many situations, if the flocks have been squeezed out of their area, some will return, giving into remembering their flock roosting and picking areas. I had the unfortunate thing happen to me, where one of the many flocks of turkeys that would walk through this field into my ranch and open fields, was built on. But low and behold, they found their way through all the construction and still to this day will go through that property to mine for their food plots.

And the smell thing. This was a great debate, as a lot of hunters thought this, thought that, but never really got into the biology of the whole thing except a handful of us like myself. Turkeys have a real weak, I mean weak sense of smell, yet they have evolved into a perfect glass telescope of ocular senses. They see color, they see differences in design, and recogonize terrain all within their sight program, a trichomatic vision just like humans. They have even put studies to work and found that turkeys can even see ultraviolet light, even in low light conditions where humans cannot. That is their uber-sense, where they can detect predators, other birds, and food, like insects, snails( snails are a great calcium supplement for the hens, so make sure you can find some aside of your plot), and certain grains that are hard to find in manures and scats. Althought, depth perception is lowered, because of the spacing between the eyes, so when you see turkeys wlaking with their head back and forth, that is how they can determine short distances. But for the weak sense of smell, both the hearing sense, which turkeys have developed, and their sense of sight keep their food plots, predators, roosting areas, nestings, and other familiar sites at bay and in their memory banks.
And to scout. I would scout at least two weeks if you can before opening season, and gather as much intel on flock migration throughout the designated areas, what kind of weather factor makes them move into what direction, look for tracks of predators and other humans, and locate their food sources and roosting areas. That will give you so much direction on where to ambush and stalk, and what type of ammo to use twoard weather conditions. Yet, with all your scouting, do not over scout the area and let the turkeys be TOO aware of your presence. That could ruin all your homework for the big day!