"2. Something GNOME-ish keeps grabbing my mouse, and won't let it go until I log in with SSH and start killall-ing anything with "gnome" in the process name. It happens once a day or so, I haven't been able to purposefully reproduce it, and it's really annoying."
That is a bug, I've not seen that on Ubuntu 12.04 using Unity or GS all through the testing period.
I gathered from what jmillikin said that it is certainly a bug, but it was probably not reported during the testing period for the same reason jmillikin didn't report it: it appears to be hard to reproduce.
Is there a tool (akin to xev) that would display which process currently has control of the mouse? I would think that tracking down the process that has grabbed the mouse would be the necessary first step toward stopping it from doing so.
That is a bug, I've not seen that on Ubuntu 12.04 using Unity or GS all through the testing period.