1. I don't know nobody with RSI or SAD
2. I think I sit correctly for use my computer. Sometimes I had pain on the right wrist
3. Advices:
- Place the monitor in front of you and at a confortable viewing distance
- Adjust the position of your chair to give you a comfortable viewing distance and posture
- Your forearms should be roughly horizontal and your elbows level with the keyboard or the mouse
- You should take breaks before the onset of fatigue, not in order to recuperate
- If possible you should take your breaks away from the screen, and avoid activities that requiere actions similar to your work (writing for exemple)
4. The exercises are very useful.
5. I don't do exercises. Only once a week I'm going to swim.