I have a 2012 MacBook air and thinking of upgrading and have a few questions. 1. Should I upgrade to a MacBook air (when the newer verison gets released) 2. or get the MacBook? what is the difference? 3. Once I get the MacBook air, how do I backup or move all the stuff that's on my current laptop? 4. Can these be easily sold, or better to wipe it clean and give to a family member?