Mark, those are some excellent questions and I'm not sure if I can provide an answer but I'll throw my own $.02 in.
As far as how a hen knows when to rotate her eggs during incubation, that has to be purely inherited maternal instinct, because that is not a learned behavior that a turkey picks up during any point in her life. It's not like she gets to watch her mother rotate her brothers and sisters because she's trapped in an egg herself. After she hatches she's still unable to watch her mother rotate eggs because the rest of the clutch would already be born. By the time that little hen's able to watch her mother on another clutch would be the following year, and I'm sure her momma would already have ran her off by then. As far as the mechanism of how the hen knows which eggs she has turned, I'm not exactly sure. Could be due to both instincts and memory. I honestly wouldn't be surprised if a hen has a good enough short term memory to remember which eggs she already rotated. And I'm sure there's cases where a hen forgets to roll one egg or may roll the same egg twice...everybody makes mistakes.
Moving on to smell and taste, I agree with Charlie that a turkey can smell, even if it's at a basal level. It's not anything close to that of mammals, but I do believe that a turkey has a slight sense of smell. As far as taste goes, I would also have to say that they have some sense of taste, which is probably better than their sense of smell. For example, if you like hummingbirds and you want to attract them, you set out some sugar water in a hummingbird feeder outside. If you wanted to test them, you could put 2 feeders side-by-side, one with sugar water and one with plain water, and they will go to the sugar water every time. How do they do this? Do they smell the sugar? Do they taste it? Both? I don't think anyone really knows the answer to that question, but the same scenario can be applied to a turkey. Just like deer, they prefer white oak acorns over red oak, even in a red oak mast. Some people believe it's because of the decreased levels of tannic acid in white oak acorns, which is responsible for bitter taste. So if white oak acorns have less tannic acid, they are less bitter, and are instead sweeter in comparison to red oak acorns, which indicates that a turkey is able to taste a difference between the two acorns.
All of these questions you guys have posted on here are really good questions, and I'm not sure if even the most highly acclaimed wildlife biologist could give you a real clear-cut answer. There's always a study that support one idea, while another study may totally refute the same idea. People have different experiences that affect what they believe, that's why I love conversations like these so much!