There is very little brood and it appears to be hatching. It takes 21 days from egg to hatch for worker bees, so it looks like you have not had a good Queen for 18-20 days. Possibly a bad Queen or she got injured some way. I don't think that swarm came from your hive, if it had you would have lots of capped brood. If there is a new un-mated Queen in there it will be about 25-30 days before any new brood hatches. If you buy a new Queen it will be 3 days to introduce her, and a day or two before she starts laying. If you wind up with two Queens they will fight to death of one or both.
You could watch that Queen cell for awhile and hope it was started from a good larva and hatched a good Queen and that she come back from her mating flight. All the indecision's is what makes raising bees so much fun. Good luck and keep us up to date.