Hi Jack be careful that you don’t fall into the trap that I fell into when I first started out. I used to spend a lot of time chasing swarms, while at the same time, my own hives were swarming. After the penny dropped I stopped chasing swarms & concentrated on preventing my own bees from swarming.
It was amazing some of the reactions people had when we said that we don’t chase swarms. “Don’t you know that bees are in trouble” or something like that was one reply.
Anyway it’s a great way to build up colony numbers while starting out. Plus you’re gaining a wealth of experience/knowledge.
On the frame of brood issue: you’ll quickly discover that any of the recently hived swarms in single boxes will provide a readily available frame of brood at short notice.