A:AnswerYes you can. I don't know if it comes with the wiring needed but if not you can buy a Seagate Barracuda 2TB @ 7200 RPM for 70 bucks. The wires for 3-5 bucks and you're set. You got an amazing system.
A:AnswerIt sounds like one of the sticks of RAM may have loosen during shipping. I would suggest contacting customer support to fix the problem or to have someone fix it for you since it is an all-in-one. Good luck!