Steve - it sounds like you have it correct; your explanation was very clear. I've done some work for an autobody paint shop and the installation methods you mention is how we did it.
By the way - there is a book out just on the subject of wiring methods in hazardous locations - I saw it at abebooks.com (1993 code) reasonably priced [$10-15?] I used their search engine - 'National Electric Code' and that book came up on a long list of books available.
