Harry Mason has a nice tutorial on biots on his site.
http://www.troutflies.com/tutorials/biot/ You will obtain very different effects by wrappping the biot on one side or the other.

I place mine on a warm wash cloth if they are brittle. I don't coat the body, but I do place a small amout of head cement on the area I am about to wrap the biot over. This just adds a little durability IMO.

I use them for wet flies and dry flies.

http://www.flyfishsouth.com/upload/stev ... CF0002.JPG

http://www.flyfishsouth.com/upload/stev ... dQuill.jpg