No, Do not short the Nifty here
Yes, Buy the Banknifty in options
No do not sell off your holdings they will no tbe available at better prices later.
Yes, you can use the same int5ra day strategies tomorrow. Buy and keep Cipla if you have to invest the Cash.
Yes hold on to Nifty Calls
No this is neither good fro a straddle or a strangle, if expectibng low vol that is just the morning session or the afternoon sessions, moves are quick and decisive, only to return int he opposite direction and they lost volatility from 30 to 15 till last week they may not gain much of it back