Ok - I'll chime in . . Structural Engineer, with degrees and official
License who has designed many buildings.
the 90# for a 16d box nail is about right on . . to start with.
There's a lot of factors that could increase or decrease that number
by a factor of two or so depending on exactly what's going on and what
kind of loads you are holding up (for example:short duration loads
like wind, multiply by 1.6; hot, wet conditions might be multiplied by
about 0.6 or so)
Steel strength for get's pretty meaningless since it's wood that
always fails in a proper joint, but the minimum steel yield strength
for both nails and wood screw is 70,000 psi to 100,000 psi. Neither
nails or screws are usually heat treated.
Normal screews are usually not hardened; however, this thread started
somewhere way back when talkung about dry wall screws which are a
different ball game.
SFWIW, also have the shingle issued by the state hanging on the wall.