Thread update: it probably took ten hours of fiddling around, internet reading, and calls to Garmin's CS (and questions to a user's forum) to get the Edge 530 configured to my preferences. It has a very unintuitive user interface, and the online manual is a joke. Once I was finally able to start using it in earnest, I figured out that the companion app (Connect) was draining my iPhone battery to an alarming degree. Around this time, Garmin pushed out a couple app updates within a week's time or so, and so I updated it, hoping this would solve the phone battery problem. Instead, the outcome was that the computer now fails to pair with my phone each time I use it, which necessitates un-pairing the phone and computer, then repairing everything (phone, computer, app) and going through some of the initial setup again. FOR EACH RIDE.
I finally gave up and ordered a Wahoo Roam, which I configured in about twenty minutes, and which seems to stay connected to my phone without difficulty. Oh, and on today's ride, I decided that I wanted a data screen set up differently, so I whipped out my phone and changed it while riding.
The Garmin is going back. It's great in theory, but in practice it's $300 worth of frustration, at least for me.