You sound like me! I won't go into all of it, but I come from a similar background, could not digest fat for the life of me, or protein (animal flesh) either.
Liver flushes changed that. You have done tons of reading, that's obvious, bravo! Now it is time for some field experience IMHO.
Do Moritz' flush and see with your own eyes what is in the body, contemplate it, weight it against all of your book knowledge, and you will come out the other side a true expert, no doubt, who could really help some people around here.
I don't have the answer to all of your questions, I don't think anyone does. BUT, true wisdom comes from first asking the right questions, which I don't see a lot of "experts" doing. They get focused on doling out info, not learning. If you can pursue this line of questioning, you will get far I believe.
Regarding needing fat to detoxify, I believe in the current state of our health the answer is YES! Reason being, the toxins are put in the bile, the bile is recirculated, hence so are the toxins. This is why coffee enemas are so genius, they cause an excretion of bile, so it isn't recirculated and toxins leave forever! Do you do coffee enemas?
Too much protein is probably more deleterious than too much fat. Either get calories from fat or carbs, not both. This is tough when trying to detox, though and will have to be finessed.
I can't mentally get over the bad effects of eating cooked food, but the body is able to over come some things in ways we don't understand.
Liver flush enough and you will digest fat again, use real olive oil from California.
I am pondering some of your other questions today and will write back in later. Ciao!