About sewing over pins-I remember in high school during home ec, I was told it was ok to sew over pins if they were placed correctly. Was my home ec teacher telling fibs or was it the thing to do a <cough> couple years ago---ok 30 ish years ago?
I rarely sew over pins now.
I cut under my arm with the rotary cutter, I hold the fabric and ruler with my left hand and cut under the arm with the rotary cutter. I always check to make sure no new people are around when I cut because I don't want them to pick up that bad habit.