I would SKIP 2 exercises -- the ones that are causing you pain, good mornings and SLDL. There's a very good article on here somewhere that explains why some people should never do good mornings.
Form is tricky, too. You may be arching your lower back MOST of the time during the movement, but for just a short split second it may flex. This faulty motor pattern has been observed in a highly trained powerlifter in a laboratory. The brief flexion would be impossible to notice except by examining a recording. But in that short moment with heavy loading, flexion can damage the disc.
Strong abs do not protect against back injuries per se. Instead, it's endurance of the stabilizers that need to work in proper coordination. A lot of the suggestions on this thread should help, like planks, walking around with dumbells, etc. Do them for a long time to build stabilizer endurance. These are not bodybuilder muscles; they need to work to stabilize the spine every second of the day.
Finally, scrutinize your posture. If you have imbalances that push your head forward, round your shoulders, raise one shoulder or hip relative to the other, tilt your hips forward, etc., you're in trouble. There are lots of articles here to help you analyze your needs (by Cressey and Robertson). I wish such information had been out there when I started training. Good luck.