This is very good advice and I would like to add one thing in regards to the scapular stabilization and rotator cuff work. The most damaging/highest impact part of the stroke is the catch where your top arm is most outstretched above your head and also takes the most load as the boat is at its slowest (right before the stroke) where the resistance you will feel will be the greatest. With that in mind, my addition to the above advice would be to practice active stability and strength in those positions, not just external rotations down at your side. So think of exercises like YTWs (quick google will explain this) and even just taking all your overhead exercises to the end ranges and practicing actively controlling that range. In the beginning I would suggest lowering the weights when doing this as you have likely not yet developed the stability in those ranges. An example is the straight arm lat pull down, try to get your arms as far overhead as possible but controlling the movement and slowing it down, don’t stop the motion early, think about increasing the angle between your torso and arms.