Craig, a long time ago I learned to cook over an open fire. That was "camping" when I was a kid. One reason I learned to hang the pot was you could cook easily while the fire was just started, not a bed of coals. You can keep the fire a roaring campfire and continue to cook, heat water, make coffee, whatever.
The method I learned was with a pole and a pot hanger made from a stick. If you notch it just right you can change the height above the fire for simmering, boiling and cooking. Takes a few minutes of work to make the arangement but is a very enjoyable way to cook. The pot gets really black on the bottom, so be careful what pot you use.
As for cooking in a small cup, I have, it is just not easy to cook anything large or to cook for 2, etc. I used to carry a small cartridge stove which had a cup cover when I was doing mountain rescues and used it when left out for the night numerous times. Boiled water for drinks and freeze-dried meals.
Anyway, the more methods you can learn about cooking and about how this works better, the merrier.
I have a habit on backpack trips to carry a filet mignon nearly cooked on my home grill, then freezing it in foil. Take it for the first night on a pack trip wrapped in my sleeping mat. When dinner time comes along, I warm the steak on a fire, which finishes the cooking and make a side dish on my stove. The look that people eating freeze-dried meals give me when they smell that steak and watch me eat it, well, priceless!