After some digging through the old boxes of electronics at work, I was able to find another Firecracker attached to a USB-DB9 Adapter. This answered a view questions.
The input is the female connector.
The Firecracker I was using previously did indeed work.
I also managed to plug it in to the arduino directly and have it work successfully sometimes, so no resistors or anything needed.
But it only worked occassionally. I noticed I had to "calibrate" the firecracker through the PC and then attach it to the arduino. However, it would work for a while and then randomly cut out. Has anybody else had this problem? Is there some sort of magic to it?
Please note I did read this thread and attempted the modification without success: http://forum.arduino.cc/index.php/topic,142594.0.html
Thanks