First, most low-cost servos will move considerably less than 270° total between extremes. It is safe to count on ±60° to maybe close to ±90° (180° total). The simple reason is that in hobby applications with push rods and such, one does not want to go past center. If you need more rotation, that may be obtained electronically, but there is usually a physical stop in the servo gear train that needs to be removed too. 120° should be more than adequate for any finger joint.
As for the direction of rotation, shorter pulses usually turn the shaft clockwise, if you are looking at the end of the shaft. That is not absolute. Most important, it is easy to reverse rotation in software, and that is a common part of most controllers. Rotation of servos can also be reversed by reversing the connections to the internal pot, if they have one. That was a common practice 20 years ago, but not any longer.
John