Okay, so you want to build an addition. You can find all kinds of texts that tell you what you should be doing. But no one wants to tell you what NOT to do because no one wants to reveal all the mistakes they have made.
Shingles (not the disease) are made from a variety of materials. Many people like the look of cedar shingles or the durability of clay. For my money, the only shingles are fiberglass shingles.
Like tar, roofing nails have the unfortunate tendency to migrate. If you store your nails in any proximity to an inflatable item, you are asking for trouble. It is best to store them in a well-sealed vault in a corner of the garage and under strict guard. Ask any professional roofer how many nails he has found in the front left tire of his pick-up truck.