My wife has a domestic flight CCU-DMU with Indigo. The ticket says check in counter closes 1h before departure. When does she need to be at the airport, considering that she needs to check a suitcase and has priority checking 'Fast forward' service?

Second question - on her return trip there is domestic flight DMU-CCU and then international flight on a separate ticket CCU-SIN with SQ. The flights are >8h apart, so there is plenty of time. However could you please tell how much time would it take to get from the domestic terminal to international and can one go airside and spend time to lounges? And what lounges are preferable? She flies economy, but has Pririty Pass from AMEX Platinum.