Jerry,
1. Go to
http://www.nwpowwow.com/Pictures/200...Gen/index.html and click on the sixth picture, the jr. boy tradish dancer holding a silver shield with a red and yellow-spotted elk on it is wearing the bustle described.
2. The conical effect is from reducing the circumference of the circle made of the outermost tips of the feathers. Imagine cutting a small pie-slice from a paper plate and then bringing the new edges of the plate together to form a shallow funnel. The sinew used to control the spacing between the feathers is just slightly shorter than would allow the feathers to spread perfectly flat (experiment until you find the look you want).
3. The 11yr old boy wearing the bustle is about 4' 9" tall, and as you can see the bustle is a little big on him FOR NOW but he will be growing into it over the next few years. If I remember right the dowels are 6" in length. That would be almost perfect for a 6' tall man. The extenders for the spikes are the same length, they just use longer feathers and are positioned by the sinew to be more separated from the rest of the array. In case you are wondering, his bustle happens to have a little bit of horse hair on the tips of each feather.