Changing from Steam to Mac

[Alteiriaa]

Now, I don't have the Steam version but I *think*:
1.) As long as you add the Mac licence on the same SE account as your PC/Steam version, it should be fine!
2.) Should be the same as the PS4 version, you can get it wherever you like, only time there is a issue is if you try to combine normal PC licences with Steam version ones, which do not work together.

(I'm sure if I'm wrong though someone'll be along to tell me how wrong I am. )