I'm going to break up your last post into sections and respond to each separately to make it easier for myself and hopefully easier to follow.
IMO, your practitioner is correct in that during his techniques he is helping reallign the fascia and make positive changes in the tissue. And there are few instances where just changing the fascia/tissue may restore a proper range/biomechanical position, so during your everyday activity you restore the proper activation, length-tension relationship, biomechanics, etc. But, from my experience, there is usually an underlying muscular inhibition or improper activation patterns that are causing the poor biomechanics, posture, and resulting in the poor tissue/fascia. Also, FME, the body will respond more when active stimulus is presented, not just passive (active meaning muscle re-education, corrective exercise, mobility drills, etc; passive meaning soft tissue work, manual therapists including manipulations, mobilizations, etc).
I somewhat agree with your practitioner's statement again, but what is causing your "bad habits". Are you rounding forward because the anterior musculature and fascia are tight, or because your posterior musculature is weak and unable to support proper posture, or is it both? Or could it be poor thoracic mobility due to imbalanced/improper muscle activation? To just say "don't do anything wrong" is a pretty vague statement, and it may be something that you can't just think of "oh, I just won't do that". It may be something you need to correct with exercise, muscle re-education, etc. If you have poor scapular muscular control, then your shoulder won't be moving optimally. You can think of holding proper positioning 24/7, which is likely impossible. Or, you could train those scapular stabilizers with proper corrective exercise and make it a natural body action.
The frontal assessments shouldn't have any negative effects what-so-ever. The assessments themselves will just show where your body is standing at that given moment and guide you towards what exercises would be best to correct what-ever pathology/imbalance is present. If anything, doing the assessment and the exercise in conjunction with the ROLFing would be optimal. You are combining the active (exercise) and passive (ROLFing) stimulus/therapy, which will give the best results.
Not quite sure what the difference your practitioner is trying to make between the "applying force" and hanging, as when you hang into a stretch (first stretch that comes into mind is a hamstring stretch), you are essentially applying body force. If he is trying to say that you do not want to force your body into a stretch it is not ready for, then yes, I agree with that. The body will initially respond to a stretch by making the muscle contract as a protective mechanism, but after holding it for about 10 seconds, the muscle will relax and allow the stretch to take place. There is a lot of debate over the effectiveness of stretching, but that is a whole separate conversation.
By no means am I saying that I am right and your ROLFer is wrong. You just asked for opinions on things, so I gave mine. But the one thing that I will say is that even after your ROLFing, you still have lingering back pain. So maybe there is something missing in your therapy approach to help fix the problem.