I heard from a Rov, that if one himself is not mehadrin min hamehadrin, he should light only one candle, and should not use oil, but instead light a tea candle.
If he is your Rov, get a new Rov.MMH has nothing to do with any other of your activities. In the context of the SA it refers only to lighting the Chanuka lights. if one wants to be MMH each member of the household lights each day as many lights as that day. Period. Anyone can be MMH for this purpose!
I don’t know that I’m “mehadrin min hamehadrin,” but I do consider myself to be Yireh Shomayim, and I learn because I want to know how to do Hashem’s Torah as well as possible. Even though I might not be “mehadrin min hamehadrin,” I would like to be. I do use oil — actually the pre-filled oil cup candles that are now available, and I light increasing numbers of them each night. I don’t want to second-guess a Rov, especially one I don’t know, or say that he’s wrong. Maybe he saw something about you that generated the pasak. However, I don’t think there’s anything wrong with someone who wants to be “mehadrin min hamehadrin” from doing something at that level to get some “on-the-job” experience.
I’m not sure if this is what you mean, but if you are saying that unless you are doing the amount for that night you should only do one, you are correct. Otherwise, there’s no reason one person can’t do mehadrin min hamehadrin.
You can use whatever kind of candle you like, including oil. My rav happens to hold that our wax candles have a nicer flame than olive oil, but there’s no nafka mina between one person lighting and ten people lighting.