To a point -- when you start experimenting with leadout position you find that as you move them in one direction or the other your overhead tension will get better and better, then start getting worse. It just ends up being cut and try.
Edit: Mark already mentioned searching, and Paul Walker's trim chart in another reply to one of your questions. Both are valid -- figure out how to do searches here and you'll find lots and lots of material on each one of your questions. And, maybe you'll find a copy of Paul's trim chart, too. IIRC Paul's chart doesn't tell you how to change things, but it does point to what to change first, then next, etc.