Re: your two questions:

IIRC, emacs cannot build on NetBSD/pmax, however, the Ultrix binary works fine.
I am not using emacs, but I remember this has sth to do with a dump/undump
function or sth like that.

xdm:

Try a kill -HUP at the xdm process and see what happens.  This worked for me
(now from 5 DS w/ X11 displays I am using one headless, so I cannot test this)

--
Yiorgos Adamopoulos         -- #include <std/disclaimer.h>
adamo@dblab.ece.ntua.gr     -- Knowledge and Data Base Systems Laboratory, NTUA