Are there any significant surviving examples? Have good collections of less perishable decorations like bone or stone survived? Are there significant variations among the cultures of different tribes? Are descriptions of ritual wear notably different from regular dress?
Can't speak to coastal tribes, but there's plenty of material available about more inland Eastern Woodland peoples. Obviously ceramics have survived in vast quantities. A little after your time period, but Philip Georg Friedrich von Reck's notebook from 1736 has great sketches of Yuchi people's clothing. William Henry Holmes's Prehistoric Textile Art of Eastern United States is available online with interesting illustrations of woven textiles, including those of Virginia tribes.
Key Marco in Florida was an incredible wet site that preserved exquisite wood carvings from ca. 1400–1500 in muck—the most famous of which is the "Key Marco cat". The Florida Museum of Natural History has some interesting perishable items, notably painted slabs of cypress wood. NMAI has a beautiful Calusa gold pendant dating from 1500–1700.
Hey there, I'm not sure if this will provide any further insight but it might be interesting to look at some works by the late ethnohistorian Bruce Trigger. He wrote a lot about Huron and Haudenosaunee people(s) in Southeastern Canada and the Northeastern US. His ethnographic work may provide some insight into traditional textiles used as well as colours and patterns that may have had particular significance to certain nations/tribes at different times/periods, before and after contact. I'd check out "Natives and Newcomers: Canada's "Heroic Age" Revisited", "The Children of Aataentsic: A History of the Huron People to 1660," and "The Huron: Farmers of the North."
I also know you were looking for pre-contact information so this might not help very much, but i'd consider taking a look at some of the missionary/priest correspondence in New France/Eastern Canada via "The Jesuit Relations" (I believe an english translation is available online). Some of the priests and missionaries were quite detailed with descriptions of Huron and Haudenosaunee apperances, and perhaps some of the earliest writings (around 1611-ish) may give some insight into pre-contact/early-contact art and clothing traditions.
Jesuit Relations link- http://puffin.creighton.edu/jesuit/relations/
Good luck!!