Hey Sapphire Lily! I've seen a lot of your posts here over the past year when I was a silent lurker. Big fan.
1) I think that the redness would have faded without the IPL, so I don't think that helped much. Dermastamping helped a lot, but improvements came painfully gradually. I believe that subcision does exactly the same thing as stamping/rolling, except on a much larger and effective scale. In stamping, you are poking vertically at the scars to stimulate regeneration. In subcision, you are also trying to stimulate repair, but instead of just poking at the scars, you are going underground and cutting up the scars in a sweeping motion. It's just much more intense.
2) I was very disappointed with the way my doctor performed subcision on me. I went in not knowing what the procedure was, or how it is supposed to be done. He did about two jabs on either side of my face, and pretty missed three out of the four times. As I mentioned above, he did hit the scarred area once, and at that jab I actually felt and heard my scars popping and responding to the needle. That particular scar improved. I am now looking for a better doctor to perform the procedure on me. Don't want to waste downtime on a poorly done subcision session
3) I only stamped the scars. I actually tried stamping the unscarred areas of my face to see what the difference was. Turns out, only the scarred parts have the "popping" noises and remain red a few days after the stamping.
4) Both. The most noticeable improvement was the fading of the red marks, and this required a time span of half a year for each fresh scar. But the raising of the scars through stamping has helped my appearance drastically too. I would say that the shallow scars raised more significantly than the deep scars, all things being equal.
5) I do eat healthy (not because of choice, but because I am living off dorm food). In terms of skin care, I apply Retin-A everyday, moisturize every night, and sleep with a freshly washed towel on my pillow every night. Miss any one of these three components, and I find that my pimples start coming back. It's really a blessing that I've found this method through trial and error. My skin is 98% clear now.
Hope this helped.