"And of course you'll want to attach a full-sized keyboard, too, especially for AE work."
Nah, just learn to go minimal and work with the laptop shortcuts - which also allows you to use that super nice minimal apple keyboard with no num-pad. So clean.
Also maximize that trackpad by turning tap select on and three finger drag etc. I edit entire vids with the Air using just the trackpad and built in keyboard on airplanes or in a hammock sipping a mai tai. 'Tis lovely.
Takes a week or two to get used to, but once you go minimal, you'll never go back. :-)