A few questions. I am waiting for delivery of my new 2015 13" rMBP this week. I want to do a clean install, and to that end am currently going through my 2012 MBA, deleting old unwanted or unused files etc. in preparation. Any tips to make this a smooth transition much appreciated. eg. Best way to do it. Also, there are some important emails that I would like to transfer across and keep. What is the best way to do that please? One other thing. if I move my iTunes Library to an external drive, will it only be recognised by the Mac that it was exported from?