Those are some very impressive accomplishments for and ‘old’ guy with a bum ticker! Good on you!
Before I dig into your questions here’s a disclaimer: I have only a layman’s understanding of Biochemistry and Physiology. These processes, that I am about to so casually discuss are incredibly complex. Far, far too complex to give them anything like a full explanation in a couple of paragraphs. Entire text books are devoted to this topic and several years of rigorous study are involved to understand it.
With that said: I can’t answer your question, especially as it relates to your medical condition with the stents/statins. You need to seek professional advice for that. I doubt you’ll find that level of understand and advice on any forum.
You’re correct that NADH is a product of glycolysis along with its ATP. However a more important principle product of glycolysis as that process relates to aerobic metabolism is pyruvate which can be converted to acetyl CoA in the mitochondria. Acetyl CoA is the precursor for aerobic metabolism which takes place inside the mitochondrial matrix. Aerobic metabolism includes the Krebs Cycle and the electron transport chain (where most of the ATP is released). This is how glycolysis can lead to aerobic metabolism when there is adequate aerobic capacity in the muscle cell.
Fat metabolism is known as lipolysis, of which a very crude and incomplete description is: Stored triglycerides are broken down and released into the blood as glycerin and free fatty acids. Those FFA are further converted, by way of particular enzymes, into Acetyl CoA. As in glycolysis, this acetyl CoA can then enter the mitochondrial matrix to undergo aerobic metabolism.
Both these processes contribute to the overall energy needs of the muscle cell. Slow twitch muscle has a much higher mitochondrial density so is able to aerobically produce ATP in great quantity from either fat (using lipolysis) or carbs (using glycolysis). Fast twitch muscle, because it has less mitochondria, has to rely more on anaerobic glycolysis for its ATP supply.
I hope this helps,