Good question, going forward to turn on a board with less rocker is difficult ranging up to impossible, a higher rockered tail lifts the nose even more for a turn and just makes it easier, the usual routine for a long board was to turn from the tail and move forward to trim and gain speed , the short board idea was to place all the control of the board at the one spot thereby speeding up the boards response time and having the shorter arc of board to fit the tighter and steeper parts of the wave at different angles.
The more further forward you go the more rail you have to engage in the turn and it becomes physically harder and harder,
one thing you can do when forward is break the rail and tail free and side slip side ways to a lower track on the wave face, watch video of Miki Dora at Malibu or Phil Edwards in some of Bruce Browns early surf movies and you will see all of the above.
The arching in a turn was both, style emphasis and position the body and gaining torque on the turn through body twist.
Again I would recommend watching really good log surfers and how much their bodies contribute to their turns.
BTW I place myself near the higher end of average as a surfer, I've just been doing it for a long time around the world.
My former vocations as a Chiropractor and sports coach gave me insights as to how these things are done, and sometimes I can do them too
I've taken up troll hunting just for fun, instead of a rifle I'll just use a pun!