Stringers over weave I agree with. As for amperage you've got to use what works best for the electrodes and the welder you are using. I've been on welders that have been 15 amps out of calibration.
my guess is the flux coating is thicker for better shielding so in effect its a 2.5 mm rod but the flux gives it more a 3.2 overall diameter rod size maybe most 2.5 rods I've used 80 to 85 is just about controllable