Re: Feeding swarms
I hived a swarm earlier this season in a deep with just foundation. No drawn comb, no brood, no honey, AND the swarm had a virgin queen. I did not feed them one ounce of sugar water. Its been about three weeks and that swarm colony is twice as far along as any of my packages (that have had syrup on them continually), and the queen is laying beautifully. I don't know what it is about swarms, but they build up so fast. So to answer your question: No, I don't think it's absolutely necessary to feed a swarm. (Not that it wouldn't help, though)
...This, and my heart, and all the Bees
Which in the Clover dwell.