Swarm behavior

Looking for some feedback on what I'm observing.
Second year beek who began trapping swarms this year. Already caught one, small but had pollen and drones coming in. I am located in central NY and there is an abandoned beeyard a mile from me which has not been tended in about four years. Of the thirty colonies there, two are functioning.
I built the traps to be 18x18 and hold about 40 liters. I do not use any frames with honey, just old comb for center and four frames to build out. Five frames total. I have had furious action with bees constantly in and out for the day and then the next day nothing.

I have two boxes with bees apparently residing. they are acting differently than the previous swarm. Been watching for about four days now and they are remaining in the box. Appear to be all scouts and are defending the entrance. they are cleaning, and constantly scoping the box out, measuring the inside and outside. Can't be more than 10 or so bees in either residing but they appear to be feeding the defenders at entrance. They are doing aggressive cleaning of each other on the way in. Slow but steady flow. I have a cutout on the bottom so I can look up into the box and there is not a lot of bees. What am I seeing?
How long do scouts hangout before they bring a swarm in?
How small can a swarm be?
Do they ever reside without swarming?