1) How to check Required Margin for a given commodity (generally it is 5-7% per commodity), before placing an order 2) How to check if in the current market there is no circuit condition 3) How to check bid price, ask price without checking order book
For margin details please go through this thread.
As of now, we don't have upper or lower circuit limit values.
You can get bid and ask price in market depth. Check out websockets for streaming live market data which contains market depth.
For more examples, please go through this.