I'm writing a book about a character who was born in a nomadic tribe in ~4000 BC, in the Chicago area, but travels the whole of the plains, from the mid-west to central Canada, with her tribe. I was just wondering if anyone had any clue of where I could find information.

I know it's such an old time period that likely, any customs/religions/language/whatever is long lost. I'm basing names on various other Native American cultures (namely Hopi, which is a bit off geographically so I'm also looking at Iroquois and Lakota), and trying not to be too terrible in making my own religious beliefs for them to follow. On this note, I'm mostly hoping for links to good websites to read up on. I'll be going to Cahokia Mounds this week to do some of my own research. I might also be going to Chicago sometime in the next month and seeing if their history museums have any help for me.

More concrete questions:

1. Would there primarily be animal-based clothing? As I understand it, they mostly just cared about covering major organs/staying warm in the winter. How long would it take to make these?

2. How many people make up a nomadic tribe? A dozen? A couple dozen? Over a hundred? Any idea would help. Was inbreeding common, if they were so small? How did they keep genetic diversity?

3. What was mortality like? As I have it, they don't name children until they've lived two years, as I assume that's a high mortality rate. After surviving childhood, would ~30s or 40s be a realistic end goal? At the moment, I have 40 being the time most everyone drops off, though there's one or two still kicking it in late 50s, early 60s.

I realize that there might not really be much concrete information, but I'm just at the start of my research, so any information could help.