Oh my GOSH. Get a sturdy chair before you worry about anything else. I think the reason you're sitting so far back on that wobbly thing is to distribute your weight evenly so it won't tip over. You can't base your entire piano technique on trying to keep from falling down. Then, when you have a strong and stable chair at a comfortable height, move it back... WAY BACK. You look tall and strong (aw, shucks) and you need room to play!! If you aren't sure what makes the difference, try this: sit as close (closely?) as you normally do and put your hands right in the middle of the keyboard as if you were going to play. Doesn't matter whether you play, but observe the angle of the outside of your hands to your forearms. Now move back several inches and check that angle again. Move back one more time and check again. See how the angle is getting less acute and more relaxed looking? This is healthy. I wasn't sure about your repetitive stress syndrome, exactly where you experience this. If it's in the wrist, I think you'll feel a lot better sitting back because when that angle is so sharp, it's very stressful to the wrists. Actually, if it's your fingers, this should also help, because it lets you use large body muscles for movement and power instead of woodpecker-tapping with the fingers. And, as others have suggested, sit on the EDGE of your chair. Playing is very physical-- not in a forceful way, but in a "I'm ready, I can do it" way, whereas you look like you're poised to have a martini. You have to be far enough back that there's a little room to lean forward sometimes. I used to sit as close as possible to the piano. I don't know what instinct made me start moving away, because no one ever told me to. And it scared me at first, so it's not like I did it to feel more comfortable at that moment. Who knows? At first it feels very out of control because you're not right on top of the keys. But if you try it for a while, you'll notice that you can see and feel your way around better with that bit of distance, and you might feel a real difference right away with the physical stress issues. Good luck! Be healthy!