I have never seen PP change drastically the composition of a good photo. Perhaps the WB and a crop, but a good photographer gets a finely composed slice of time which can not be significantly altered in PP.
In some 64 years of fairly intensive photography I have never felt the need to calibrate any of my lenses. I buy premium products made by my camera manufacturer and do not recall any calibration problems. Very lucky or just poor eyesight?
Been using Lightroom 4.4 for a while. Looking at the cloud monthly version and see a rather large learning curve. True?