When you build with Crosswalk, make sure you click the 'canary' version in the build dialog.
You can also select if you want to run your app in full screen, or with the toolbar showing as well.
Then inside C2, use the Browser Object, and "Lock Orientation" to whichever mode you want.
Try the above suggestion to lock orientation.
Also, Crosswalk is amazing, tested my game on a very old phone: HTC Incredible S, weak SoC and 512mb ram and it ran flawless, with perfect screen resizing! Using CocoonJS, it would never load due to low ram.
Edit: Also something interesting regarding the sound bug, on my ASUS tf700 with Tegra 3, volume control doesn't work, but on HTC devices (One X and Incredible S) it works fine.. sound bug is volume control only applies to music played, not sounds. If you guys at Intel want to chase this bug up: play.google.com/store/search