You always make thoughtful, useful posts, Bob. Good luck with your new hummingbird thread!
I just set out two nectar feeders tonight (one I just bought today) so I look forward to learning whatever your thread brings to light! I assume you need a TON of bright sunlight so you can use one heck of a fast shutter, but beyond that, I don't know. Being as small as they are, I guess a small (f/2.8) DOF would be fine as long as your little subject is hovering to eat.
This will be interesting.