F&O premium and margin

let’s say I bought 2 lots of Reliance call Jan expiry and sell it on next day. So can I buy another option position from this amount?

Yes, you can.

Yes, you can. The premium received from selling options can be used for buying options on the same day. If you wish to use it for other purposes, like shorting options or buying shares, you can only use it from next day onwards.