I still think Shaun Johnson over Tohu Harris Harris but wouldn't mind Harris as an off field co captain.Tohu Harris Harris for me.
Captains set standards, lead by example and have to be a straighty 180 imo.
Leadership on the field is your half-back hooker. Like running plays and field position stuff.
Talking to the ref is overrated imo. Barely effects anything.
And agree with your second point and think it's mainly overrated due to a very small number of captain's i.e Cameron smith etc and that probably was helped by the team he was playing for .