I am not really competent to comment on the majority of your material above.
What I would advocate, however, is that you use RAW exclusively if you wish to produce high quality photometry which is compatible with that produced by others. JPEG, TIF, PNG, et al. can do very weird things to the data over and above what the camera itself may do in the area of noise reduction, white balancing and so on.
You likely know all this; I make it clear for the benefit of those readers who may not have come across this concern.
What is the source of your “to avoid taking up too much memory” concern? Not disk space, surely, as multi-terabyte hard disks are dirt cheap these days. Let’s be generous and say a single image uses 100MB. That means a single terabyte will hold ten thousand images. How many images do you take each year?
Paul