I don't know the answers to what you've asked. I do want to share this site with you - if you may not have seen it previously:
http://www.chirogeek.com/001_Tutorial_Birth_of_HNP.htm
I'm a bit tired, yet will re-read tomorrow; I also did a quick Google search on extruding h. d. and found this:
http://www.vax-d.com/Pages/StudiesPu...enceDecom.html
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