Hans, I have many of the same questions that you have about MLF. I do not add anything to my wines to stimulate MLF therefore if it happens, it happens, if not, it doesn't.
We made wine 60 years ago by just crushing Zinfandel and Muscat grapes and co-fermenteing them in an open barrel. Yes, the Muscat skins too. We did not add yeast and only much later learned about Sodium Metabisulfite, which we used to order and pay $5 for a very small tube. Our schedule was fairly much the same year to year. We would buy the grapes sometime during the second week of October, process them into an open barrel for 10-14 days, transfer the wine to barrels with open bung holes which we had to keep "topped off" and "de-fruit flied" until about the 2 week of December. At that point the barrel would be sealed with a bung and left until about Easter when the wine would be ready to drink. Aging was never an issue. No wine was more than 1 year old in our house, unless a bottle got lost behind the newer wine.
Time and age may have dulled my memory somewhat but I remember the wine was excellent just about every year. When I make wine now, I try to stay close to that MO. The only thing I add as a matter of course is Potassium Metabisulfite.