Anyone have any idea of weight difference between conventional 10 or 13 spd clutch/trans in semis vs the newer 10 spd auto trans?

Are the auto-trans semis able to get rid of their heat satisfactorily on short distance runs in the 400+ hp combos?

How does the torque convertor "lock-up" happen as it does in smaller pickups? I assume it's not driver selectable?

Just curious.