Hi,
1. No, the Companion will only work on an Android device (tablet or phone). The emulator is designed for Mac, Windows, and Linux.
2. Any modern browser (so any Chromebook) is able to run the App Inventor website. Any modern Android device can run the Companion app from the Google Play Store. Theoretically, we support anything Android 2.1 and up (however, I don't have access to devices that old, so I can't confirm that). You can connect your Chromebooks to the Android devices via Wi-Fi (not USB).
An alternative solution would be to be to get large tablets, and run the website and the Companion in split-screen mode.
Farzeen