Re: Need some advic
I don't see a problem with opening the hive to check on them with temperature in the 50s. They are not likely to build comb beyond the divider board even with holes in it, but if you want to plug the holes anyway, corks are one option.
My bees festooned very quickly, and presumably started building comb. But I couldn't see any comb because there was a mass of bees covering it. I assumed they were working hard, and after a while they had moved lower and I could then see comb. Keep that feeder full til they slow down taking it.
Once the queen has been released, remove that queen cage. Hanging it between bars increases the likelihood that they may build comb starting from someplace other than the comb guide on the top bars.
USDA Zone 7A Elevation 1400 ft