Considering a Chromebook Pixel, Need Some Info

I plan to use Crouton to switch into Ubuntu for a few apps. How much slower does this make the Pixel? How much resources and RAM does it consume?

Steam is one of the apps I plan to install on the Ubuntu side. Is Portal or Portal 2 coming anytime to Steam for Linux?

If not, is it possible to use WINE to run Steam for Windows on Linux and how much would that degrade performance? Can I still get 30 fps on the games?