Apps running in a window can capture whatever keys they want. So Control-W is interpreted by your shell/app, not by the browser (closing the window). In a tab the browser keybindings still exist, so be sure to set "open in new window" by right-clicking the app before running.
Terminal settings are configurable and persistent.
It works on any machine running Chrome. Things don't quite work right on MacOS, I'm told, but it seems native on Windows and Linux. (And CrOS of course.)
I have the i7 model at work and an i3 model at home. Both are fast. I also have a Chromebook Pixel for situations that require a laptop.
As for monitors, both the desktops and laptops handle my 4k monitor OK, but only at 30Hz (because it's a Displayport MST model which are horrible hacks and are thankfully no longer made). At work I use a 24" and 30" monitor. Works as expected.
You can tune the density per-monitor, so you can run your 4k monitor at 1.25x or 2x density and your normal monitor at 1x density and it Just Works.
There's a dialog for setting up resolutions and relative position of the screens to each other. Attaching a screen means that it's automatically fired up with its default settings.
Each screen has the window bar, and clicking on icons there opens the respective website/app on that screen.
When closing the laptop with an attached screen, it merely disabled the display (instead of going to sleep completely) which was confusing the first time but actually makes sense and is how other devices handle the situation as well.
Also, when running emacs in the terminal through ssh, doesn't emacs keybindings interfere to much with chromeos's browser?