Hello,
1. Your position is a reflection of the amount of posts you have made. I believe it is just a straightforward ladder that is predetermined and changes automatically when you reach each mark - ie 50 posts= 5km easy etc. You can't change it, except by contributing to the forum via posts

2. The karma thing is silly, in my opinion

You can click on anyones to either applaud them (or what they say) or smite them. I would rather type my applause or dislike then hide behind this, so I never use it or become concerned with it

3. The stars are again a reflection of # of posts, I believe, but I could be wrong on that one... if so, someone will straighten it out.
Cheers,
Jon