You can dry cranberries, but they won't come out like Craisins, which are plump. Try some plain dried cranberries from a healthfood store, and if they are something you'd like, then go for it!
Sometimes I soak dried fruits, sometimes not. It depends upon the dish, and how dry, dry is. Sticky, plump dried fruits, I might not. Really low moisture fruits I do, unless they will be sitting in a batter for a while, or will boil on the stove, such as in a hot cereal.
I buy dried, wild blueberries for out-of-hand eating and ice cream topping, from the local healthfood store. I have never used them in muffins, as they are small, and I always have fresh frozen, but they are still plump-sticky, more like a Craisin, so I don't think they'd need soaking, nor extra liquid added to the batter.
If they were lower moisture, I would soak them, and use the liquid from them as part of the batter liquid. (If the batter called for 1 Cup of water, and the berries had 1/4 Cup of liquid in them after soaking, then I'd use the blueberry liquid, plus 3/4 Cup of water.)