OK, the practice turkey-roasting went pretty well. I need to allow more time for thawing next time, as I tore the skin to the left of the abdominal cavity while trying to remove the still-frozen neck, and now I know to look for the giblets in a paper pouch under the neck flap.
But the turkey came out very well (the skin wasn’t as crispy as it should have been — maybe I’ll let it rest without aluminum foil next time?) — and now I have a torn-up carcass with connective tissues and bits of meat on it. I’ve stuck it into zip-top bags in the fridge, along with a plastic tub with the drippings, and I’m hoping someone can tell me what to do with the carcass (and neck, which is still uncooked).