Originally Posted by FBinNY

They generally go one per side. Forward or back is a question of personal preference. More forward improves handling, but can make heel clearance issues, so I'd say as far forward as possible before causing a heel clearance issue.

As for the down tension system, you sometimes have to improvise so it works reliably. There's no one way, like many bike things (and life) you apply the concept, modifying it as needed so it works for you.