A1.Decreasing the quantity will preserve order book position, however, increasing the quantity or changing the price will not preserve the order book position.
A1.The reference price of the price limits (SCB Level) is the settlement price of the previous day. Please refer to the following page for price limits (SCB Level) for each instruments. Price Limits/ Circuit Breaker Rule
A1.Yes, order book information is distributed in Pre-Opening/Pre-Closing session, however, accessible information can vary between brokers and information vendors.