1. No. I don't know any people with RSI or SAD . I believe that SAD is not usually in Barcelona.
2.Sometimes I have a little back pain and I think that's because of I don't sit correctly during my time job
3. Put your computer in a correct position for your vision
Put your back into line
Walk during 5 minuts every hour
Choose a good table light
Ask your boss to put your table near a window
4. I supose, but I never do it
5. I never do any exercise during working. Afte work I do pilates and I think that it's very important do some exercise.