Concerns about reselling new sealed iPhone bought from an Apple retail store

If I bought an iPhone from an Apple retail store but later found I no longer needed the phone, and I have not unsealed the box, and have decided to sell it to person A: 1. Will person A be able to extract any private info about me through the serial number? 2. Is there any concern for me to sell it to others? 3. Whether I asked for a receipt or not, does Apple keep my info to be associated with this phone with this particular serial number?