Booting from an external drive

[Dale R. Worley]

I recently got into a situation where it would have been convenient to
put a "system" disk for one computer (a disk with Grub boot, a Linux
image, and the disk partitions) into an external enclosure, plug that
into a USB drive of another computer, then get that computer to boot
from the external disk.

This leads me ask these questions.  I hope that the answers are
well-known.

1. Once the computer chain-loads the boot from an external disk, I
assume Grub is smart enough to fetch phases 1.5 and 2 and the boot image
from wherever it was loaded.

2. If grub.cfg on the external disk is written to locate the the
partition using UUIDs or other location-independent identifiers (as
opposed to sda1, etc.), Linux can boot up.

3. Is there a way to write grub.cfg to locate bootable drives attached
to USB ports, offer them in menuentry's, and chain-load them?

4. Bonus points:  Is there a way to load a USB stick with Grub and such
a grup.cfg so that one can boot a computer off of the USB stick, from
the menu, select an external disk, and get that Grub to chain-load the
Grub off the external disk?

Dale