Not the GP, but I was able to pick up a new 4gb model from the Acer online store a few weeks ago (the Canadian store - I don't think Acer is selling it new in the US anymore).
If you're unable to find one I believe the new Dell Chromebook 11 is fairly similar.
For developers, installing Crouton turns the Chromebook into a fantastic portable machine. My Acer c720 has been able to handle everything I've thrown at it, and generally lasts a full day (10-12 hours) between charges.
I don't see the problem. Google is letting people pay to beta test their product. They aren't forcing anyone to buy anything nor are they marketing it as a finished product.
I'd be very interested to hear how you think brute forcing my 22 character password is easier than stealing my laptop and fooling the fingerprint sensor.
I generally have two different Linux installs on each of my computers: A Gentoo + XMonad environment for development, and a Debian + KDE environment for anything else (other school work, movies, word processing, etc).
I believe you can simply remove Facebook Home from the HTC First to return to stock Android, though I'm not sure that guarantees updates like the Nexus devices do.
To be fair, Apple (and I'm sure Google) does this too. There is no doubt in my mind that Apple is going to announce a milestone of it's own tomorrow[0], a day that just happens to be the day of the Google I/O keynote.