As to the Mac, of course you are correct, I should have said a unix type system instead of Linux. The origin is of FreeBSD as you state. Certainly one of the most closed software bases historically. I am reading and trying to come up to speed on Mac as quickly as possible. I believe I read that prior to Yosemite, maybe the one before it, X11 was removed from the OS. Although, I read it can all be reinstalled. I was looking at trying to install a particular program, from Linux world, in the Mac and it gave a pathway to reinstalling X11 and some other things that would restore the environment to allow running the program.
As to the Mac Air in general, I think I like it. It is starting to grow on me I think. Still getting used to the keyboard. The GUI is certainly pretty and as always it's just a matter of getting used to a different way of doing things. My son, who's a Cisco/IT guy, said get something called Cheatsheet to try to learn the hotkey combos.
I'll get there. Just a matter of time.