Nice work! I bet that this coating is harder, thicker and more durable than all the other coatings (Opti coat, sol-gel, glass coat, etc) that people put on headlights. Do track the durability and how it fares over a period of time.
No need, that's the beauty of it. It's supposed to fill in the sanding marks as it will self-level and cure.
But I should've followed up with 1500 grit because if look closely still can see the 1200 grit marks, that is if you look as close as 10cm away. Other than that, quite satisfied with this, but not cheap, costs SGD 95 which can do 10 sets of headlights.