Marc,
 
  A LISTSERV password  empowers you to use  the AFD and FUI  commands. That is,
they cannot  subscribe to a  file and generate load  on your server  unless you
accept to define  them a password, except  for local node users  and except for
users for whom you are the nearest LISTSERV  -- in that case the PW ADD command
is automatically  accepted. Please  note that this  is a  USER-TAILORABLE exit,
LSV$PW, and I only provided a sample one which I think is reasonable. Feel free
to modify it to  suit your needs, it won't appear any more  in the future ship-
ments :-)
 
  Eric
 
PS: I'll reply to other questions later on the list.