I did 1/2 plywood G1S on the lower 4' of wall. (for a clients house) 1/2" with 16"o/c will be fine. You can use flexable/paintable caulking between the 1/2 drywall and plywood to seal up the seam.
I also glued plywood to the lower conc/fdn kick area. Left a little crack at the bottom so no...