I've done all three of the methods I mentioned with my Sorority and I've never had problems with them being too stressed to eat if I simply net them and they remain in the water. Obviously they're a bit confused, but once they see theres food, all that changes
Eventually they learn to associate the net or breeder box with food and it becomes a pleasant experience for them. Net=feeding time....and the #1 thing that motivates all fish IME/IMO is food. ;)
Bettas are smart though, I did have issues with trying to feed on opposition sides too
They figure it out eventually, IME. Though its worked for some...
Feeding rings are neat little things, good fro training your fish, but it probably wouldn't help the bully issue much. ;)