When you attach sheet rock do you attach it horizontally or vertically? The
floor to ceiling height is 8', and wall studs are spaced 16" OC, so it would
work either way, just curious if I should them horizontally (one on top, one
at bottom) or vertically?

I am leaning to installing them vertically simply because it is easier for
one person to handle, and any uneven-ness on the ceiling is probably easier
to deal with for a 4' width at a time. Does this make sense?

Code calls for a screw every 8" so I would do that along the edges.
However, what about the two studs in the middle? Do you put screws every 8"
from top to bottom along those studs too, seems like an overkill, or may be
not?

Thanks,

MC