To address the last part of your post, I thought I'd chime in with what my team has discovered. We bought a couple of cheap servo testers from Amazon, specifically this one:
http://www.amazon.com/Andoer-Tester-...s=servo+tester
We attached it to a 4-AA battery holder and power switch and now we have what we call the "Team 2706 Handy Dandy PWM Tester". You can plug servos in directly, of course, but you can also pop off up to four PWM cables from the RoboRio, plug them into the tool, and verify that things are working. This was extremely helpful in diagnosing bad PWM connections or broken motor controllers on the robot.
These will also be useful in the future for prototyping mechanisms. You'll still need a 12 volt supply, ideally with circuit breakers, but you won't need to interface with a RoboRio or Arduino for basic tests. You could drive up to four motors/servos at the same speed so you could use this to control a prototype intake/shooter for example.