I don't have any more to add really, great tips here. I had a TON of pain for about four weeks (plus or minus, can't quite remember) with my little guy when he first latched on - i think it's relatively normal and it seemed to just suddenly disappear for me.
Beyond that - i am awed by your commitment to get this right. You have certainly come to the right place to get support and advice from experienced mamas (with twins, specifically). Keep up your great work. It's really exhausting in the beginning (and i only had one!) but the effort is worth every second in the long run.