Well, short track blades are rockered and slightly bent to make turns easier - they're also a little offset to the left so you don't boot out when you lean.

Long track blades are rockered only. They don't have the bend because they have a heck of a lot more straightaway to contend with I believe. (And their turns aren't quite as sharp.)

We do go only one direction incompetition. In practice we do some work the other way. I know most shorttrackers do have a slightly large left leg for this reason. But realistically, the only time there is a difference is when you are doing the pivots around the corners. The rest of the time you are using both of your legs pretty equally.