No way, lots of people have done that. I even installed a BIOS compatibility hack into the EFI ROM and installed stock Ubuntu 10.04 on it. Disconcertingly, it seems more responsive than the ChromeOS!
Isn't that just the "Reset to Factory Defaults" switch?
depends on how hard you press it,
No, developer mode is something you have to do if you want root access to install Ubuntu or others.