Answer: It sounds like a wonderful place. You should be able to rake away some of the leaf cover on the bushes, but leave some as a mulch to hold in moisture and provide nutrients. (Compost what you rake away, and add it as a mulch too.) Wild blueberries are simply the ancestors of the newer, cultivated berries that have been bred for larger berries, among other things. I'm not sure if the plants would cross-pollinate, but even if they did you wouldn't see the results in the berries -- the crossing affects the seeds, not the current year's berry crop. (Though having several varieties around does increase fruit production of cultivated varieties.) Blueberries are pollinated by honeybees, and probably other bees and insects as well.
You should be able to introduce some shade-loving plants, but if I were you I'd try to keep as much of this lovely habitat intact, as a haven for wildlife (and you!)
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