1. I haven't. But I am not sure that all of my friends haven't RSI or SAD.
2. I make sure that my site and type incorrectly when I use a computer or typewriter.myopia.
3. Play sports
Get a comprehensive body exam.
Use proper lighting.
Upgrade your device
Take frequent breaks.
4.I think they are useful.
5.Sometimes. I'd like to do some finger and wrist exercise. Then I move my neck. They can help me relax my body.