I am arriving at BKK on Korean Air from ICN around 1pm, and have a connection to Thai Airways to CCU at 1145pm. (separate tickets)

If I am not checking bags, can I just go through the transfer security, and hang around at the airport? I am not sure if I will already be able to check-in and have a paper copy of the boarding pass for the Thai flight - will they still let me go through transfer security, and pick-up a boarding pass at the Thai transfer deck?

If I have to go through immigration, how early does Thai allow you to check-in at the counters and go inside? I have J ticket and can use the lounge.

I know I have the option of going to a hotel close by, or storing luggage and going into the city, but I wanted to check if I can just stay at the airport (I have longer layover in Bangkok on the way back and was planning to explore the city then)

Thank you in advance.