You have gotten good advice on the pins. I also stitch in the seam when I stitch in the ditch, but I do press to one side, as someone said.
I wanted to offer a suggestion that I wish I had figured out about a year ago. The quilt gets very heavy as you are quilting. I was continuously fighting gravity until I learned to place my ironing board to the left of my sewing machine, perpendicular to the machine, and let the ironing board support some of the quilt's weight. I do have to be careful not to knock the board over if I pull too hard on my quilt. :) Anyway, it works well for me. I find the quilting very satisfying, and I hope you do too.