I believe I answered the "accessible" question plenty.
As far as securely fasten, I guess it was me who indirectly started the AHJ thingie.
What I meant in our area the AHJ requires us to have the materials either listed, or per code. As far as their authority they have the authority to adopt a code and a listing. They don't have authority to pull rules out of the air(for instance they can say:"we'll adopt the 2011 NEC starting July 1st 2012", but they can not add new rules to the code they adopted. or as many states did, they didn't adopt the AFCI change in the 2008 code, so they don't enforce it)
The securely fasten is a very gray area, just like the "neat manner" area. To me if it won't move under the normal conditions the area is supposed to be affected of, it's securely fastened. To others...... well.... I have seen inspectors pulling with all their might on a conduit and claimed it's not secured. Never mind the fact that said conduit was inside a wall, how many kids will REALLY swing from a conduit inside a wall?
In our area the AHJ will allow us to use tie wire to secure conduit, never tried bent nails. But then again, bent nails means a wood structure, which in our area means a house (pretty much everything else is metal and block). And in a house we'd use NM cable which we secure by staples(which are similar to bent nails).