Your psn is saved to the Sony servers, so you won't need to worry about that. Just make sure you require a password to access your psn from that Playstation or remove it from your Playstation. Anything you can play offline (game campaigns etc.) you'll have to save onto a usb if you want to keep your progress. Just go to settings, and somewhere in there you'll find how to save game files. Can google this too for more info. Anything for online play(destiny profile, call of duty online etc.) is saved to that game makers server. That you do not have to back up onto a usb. Games purchased on ps store will always be available for redownload from that specific psn account. Good luck. Hope this answered your questions.