I'm flying round trip to Cambodia from Bangkok on Bangkok airways. When I return from Cambodia I have a flight on Delta back to the US - 4 hour layover.

1. I have two pieces of luggage, one I will bring with me, the other I was considering using Chubb storage if available

2. On my return to BKK I might try and check the bag I bring straight through - I heard it is possible for an airline to do that even if it is two separate tickets

When I return to BKK given that I am two separate tickets
1. Will I need to go through Thai customs?
2. Assuming I do store a bag, I am presuming I definitely will go through customs, and then have to check the bag. Is it an issue checking luggage at two different times (one at PNH and one at BKK)?