The terms are a bit confusing. "Dark" tobacco varieties, whether air-cured or fire-cured, typically have larger leaves that are a darker green than varieties that are not "dark". They also tend to have a more dense covering of trichomes (the fine "hairs" on the leaf surface), which causes them to be stickier than non-dark varieties. And they are usually stronger and thicker. There really is no meaning to "light-air-cured" and "dark-air-cured", when it comes to curing technique. You just "air-cure" them. The "dark" varieties just come out darker, regardless.
Most dark varieties can be either air-cured or fire-cured, depending on whether or not you want to add the "smoky" aroma. (Fire-curing originated from the need to prevent air-curing tobacco from molding in a very damp season. The barn air was simply heated to dry it out a bit, but with an open fire, rather than venting the smoke out of a chimney or flue. It's a throwback to the early-to-mid 19th century.)
I really wouldn't worry too much about the details of specific varieties during your first grow. Enjoy the experience, and observe the differences in the plants and in the final leaf that you use. Nearly everything we grow will be different in our second year of growing, because we learn so much that first year. Relax and have fun.
Bob