Rating issues

It's not so much that I feel the need to get every rating on everything I climb, but I do tend to rate a lot, so I had some questions about ratings. 1. If a climb one does is upgraded or downgraded by less than one whole grade, are you required to change it on your scorecard? 2. If the climb is upgraded or downgraded by more than one grade, and the person re-rating is of vastly different physical shape, i.e. height, reach, how can the grade truly be determined? 3. Can gym problems, even when graded by high level climbers, be truly comparable to real rock, I say this because especially around here, the rock is extremely sharp, and often all holds are extremely painful, where one fall can tear open a finger, hand, or your entire face and chest if your not careful. Thereby, I find that due to the sharpness of the holds, perhaps the difficulty of use of them (Not so much for grip difficulty, but pain threshold) should be taken into account, alongside the moves and strength. Any advice would rock.