depending on his requirements:
the macbook pro is more for 'heavy lifting' applications like video editing, application development, etc
the macbook air more for run of the mill word processing, spreadsheeting, web browsing, email, etc.
macbook pro's tend to have higher spec processors, ram, hdd's, etc.
torrents abound, but are not as prevelant.
kogan's would be overseas stock, and thus may have issues with warranty. i would stick with buying from the australian apple store. look for the education discount store here:
http://store.apple.com/au-heddiscount is not huge, but better than nothing...
pity he doesn't want a surface. surface pro 3 is a beast.