Greg,
I believe the directors are voted in by the sitting members. The members remain on the board until they quit, voted off or die.
The HD proxy statement contains a lot of information about nhra's finances. I'll try to post some of the financial statements from 05,06,07 when I figure out how to do it.
Besides giving/paying out a few percentage points of the money it brings in each year a 501(c)(6) must meet at least 7 characteristics to receive a "grant" of tax exempt status. The 7 characteristics are fairly broad but there are some very thorny issues that could trip any 501(c)(6) if they don't stay on their toes.
lots of easy to read stuff on 501(c)(6)
http:
www.irs.gov/pub/irs-tege/eotopick03.pdf