No problem to fly below S speed.
The only reason that the bus doesn't slow below S speed when speed is managed is so that you can retract the slats and still be managed. S speed is the min speed to retract flaps slats to 0 that is it.
Min maneuver speed for the existing weight and configuration is shown by VLS
As far as going to 2 and back to 1. Airbus discourages this and although it does lower the nose of the airplane it increases the fuel burn.