Totally agree, especially 1 is super important and not always easy. Plan for a dual-stage bootloader from day 1 so there's always some rescue code to fall back on.
The LED comment is interesting. I've been on several HW development projects with LEDs as the main UI and early on I decided I wouldn't participate in UI discussions on general principle because it got so contentious. We actually have detailed corporate standards on what to do with LEDs but I've also heard some interesting decrees like "User shall never see a red LED because it looks like the product is broken."
A considerable part of the population experiences eyestrain from blue leds. They can induce headaches and when used in the bedroom you risk disturbed sleep cycles or difficulty falling asleep.
The LED comment is interesting. I've been on several HW development projects with LEDs as the main UI and early on I decided I wouldn't participate in UI discussions on general principle because it got so contentious. We actually have detailed corporate standards on what to do with LEDs but I've also heard some interesting decrees like "User shall never see a red LED because it looks like the product is broken."