What’s the minimum amount of oil for making popcorn

Use a carbon-steel wok! The shape works very well to keep the unpopped kernels in the hot oil, while the popped kernels end up on the cooler sides. I usually use about 2 T of oil and 1/3 c of popcorn to make enough for two people.

If you want to keep with the Chinese theme, Szechuan peppercorn-salt goes extremely well on popcorn! To make it, grind Szechuan peppercorns and kosher salt in a spice grinder.

While movie theaters do often add flavoring agents (e.g. Flavacol) during cooking, that's not all they do for seasoning— they also use popcorn salt which is simply extremely finely ground plain salt. Morton, among other salt companies, package it for sale in grocery stores. It sticks perfectly to popcorn with absolutely no liquid or fat whatsoever. If you can't find any, and don't feel like ordering it online for some reason, putting salt into a high speed blender, spice grinder, mortar and pestle, or some other grinding device does the trick.

For a sweeter corn, you can use a shake of confectioners sugar. It would be great with a shake of cinnamon.

I love to add a touch of garlic powder and a shake of smoked paprika to mine! My wife absolutely swears by brewers yeast for her popcorn... she even brings a little jar of it with her to the movie theater.

Good luck and happy popping!