Ok so I just ordered my first ever Mac and went with the 21.5 iMac. I've heard it will be so much easier trasferring photos etc from iPhone to Mac as opposed to the of I currently have. I am in the process of backing my iTunes to an external hdd to prep myself for the move. Am I able to use the same external hdd? Will it be a free upgrade to Yosemite or will it be on there? I assume get it started up iTunes etc transfer my photos and music and I'm good to go?