Our team is trying to use pixy for first time too. Try searching CD forums for 'pixy'. I found a number of threads discussing all your options. I found the pixy docs helpful to figure out how to connect the pixy to roborio.. particularly these two pages on their wiki:
http://www.cmucam.org/projects/cmuca.../Porting_Guide
http://www.cmucam.org/projects/cmucam5/wiki/RoboRIO
About the gyro, I'm assuming you meant using a gyro related to aiming? I'm also going to assume the gyro is mounted to the robot to measure how far robot has turned. You want take the output from the pixy and use it to determine how far off you are from your target(think degrees left/right). Then tell your robot to turn left/right to line up with the target. You can use the gyro to measure how far your robot has turned so it knows when to stop turning. I can't help you much with details or sample code b/c we are a Java team. There are many threads on CD that talk about using vision to aim. The basics are the same regardless whether you use a pixy or some other type of camera.