The 11" Air is a great device - don't be worried about the screen size. rafark expressed some concern about that, but, as he points out, while its about the size of a iPad, its a real computer. I've got a mid-2011 11" which I've used as my primary and travel computer all that time.
If there is a concern on my side would be the 2GB RAM. Oh, and how much storage memory. While the tasks you propose shouldn't be too difficult for it, you might find it struggles with anything too complex, or any multi-tasking / keeping too many apps open at once (remember, unlike Windows, closing a window does not necessarily close an app). This RAM limitation might make you consider the OS upgrades available. So Windows might similarly struggle - and that might also be a consideration re: onboard storage. As far as that goes, if its 64GB, I believe the OS at the time used somewhere around 24GB of that. So can be a bit of pinch if you start loading apps. Ditto, additional OSs. I'm not sure if Boot Camp or Parallels (an app that that lets your run Windows within Mac) lets you run Windows off an external drive, if storage an issue. Meanwhile, there's Crossover - a product that runs many individual Windows apps in MacOS. If its 128GB drive (as I have, along with 4GB RAM) there's lots more wiggle room.
Then again, for $100 - cheaper than a lot of smaller Android tablets - you'll get a computer that can handle most tasks and connect to most peripherals.
