gtk-engines 2.12.1 is available from http://ftp.gnome.org/pub/GNOME/sources/gtk-engines/2.12/
Yes, and it is part of GNOME-2.20, and we are working on moving all of that to portage. We can't put it in separately early on out of p.mask as it will break some themes from gnome-themes-2.18 as far as I recall.
This is in portage, marking as fixed.