I'm quite interested in learning more about their behavior. They tend to fly quite erratically so the better I can understand what they might do, the better I can frame up shots or know where to spend time setting up and waiting for the kind of shots I'm looking for. Hopefully it's not all about running and gunning.
I don't know about any literature, I found out for myself what they do - it's pretty regular. For example the "Heidelibelle" types above rest on noon and even retreat into the woods. If you happen to see one there, you can probably point your macro lens only a couple cm away from it and it won't fly off.
The other good opportunity is when they're looking for weeds in the water to lay eggs, they're really busy then and don't care when you come near them (or preferably wait standing in the water where the best spots for their eggs are).
What shutter speed will allow for just a tiny bit of motion blur? 1/1000s or 1/1250s?
I've tried this with my 60d back then with bees, I found it essentially doesn't really matter that much. Even 1/8000 is not enough to motion-stop an insect in full flight, but as with the wings of kolibri they tend to freeze in the air for tiny moments - that's when you have to get a lucky shot. Essentially I wouldn't trade off iso vs. shutter too much, better get a deeper dof for less oof shots - 1/1000 should be enough.