The piranha is your standard stbb. This youtube user
YouTube - Invictus0's Channel has most spyder dissasembly videos, and your piranha is basically the same as that red electric spyder he's taking apart. They're very useful for first time stbb owners. Watch them, learn how to work them. They're rather simple but easy to screw up if you misplace a part here and there.
And if you have questions just ask away.
About the charger, does your marker have a rechargeable battery in it? If not, you'll need a 9.6v paintball rechargeable and a charger. otherwise just use it with a premium lithium 9v.