Great question! I would let them know that you have pain standing upright and rate it on a scale of 0-10 (0 = no pain) and what kind of pain it is (throbbing, stabbing, dull, sharp, radiating down into your legs or up into your back, etc.). They still may want to know if your pain changes (goes up or down) as you bend forward or backward. Those changes can indicated different injuries/pathologies as well.
Sorry, I missed this question. All techniques and norms come from this text: Michael P. Reiman. (2016). Orthopedic Clinical Examination (1st ed.). Human Kinetics. Lumbar Flexion = 60deg Lumbar Extension = 25 deg Thoracolumbar Lateral flexion = 25deg Thoracolumbar Rotation = 30deg. I hope this helps!