I hear you, I been getting that cracking sound at times too. Try hanging up and calling again. I don't think it's software or phone hardware related. Might be carrier related. About the heat figure out when or what kind of use makes it heat up. Run a bunch of games or any processor intensive usage app and then have the Apple rep touch it. Use the same apps on the display models at Apple to see if they all heat up the same or if it's just your particular device with the heating issue. Try going again and speak to a supervisor or manager. Hope they take care of you.