hi,

  (I'm late I know: I was on vacation for skiing... :-)

  Matthias you stated you wanted to look out for a mac, 
and in the mean time you probably have one already fitting
your needs, but...

  you listed explicitly some intresting parameters, but
you didn't say it must be PPC...

  once your pt. 1. -the most important I'd say- is 
overcome (I haven't seen any progress as answers upon 
<http://mail-index.netbsd.org/current-users/2004/06/17/0008.html>
<http://mail-index.netbsd.org/current-users/2005/01/02/0010.html> )
a WRAP board from pcengines.ch would be unbeatable
at your pts.5 & 6 an nice-pts.1 & 2

  to fulfill your pt.3, an USB kit is also offered but
requires some soldering for install
  (I'm not informed on mini-PCI-to-USB adapters...)

  but till it is so...  sorry for x86 noise on this PPC list  :-O

Stephan